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![Christoph Hellwig](/assets/img/avatar_default.png)
A szybot reproducer that does write I/O while truncating the size of a block device can end up in clean_bdev_aliases, which tries to clean the bdev aliases that it uses. This is because iomap_to_bh automatically sets the BH_New flag when outside of i_size. For block devices updates to i_size are racy and we can hit this case in a tiny race window, leading to the eventual clean_bdev_aliases call. Fix this by erroring out of > i_size I/O on block devices. Reported-by: syzbot+1fa947e7f09e136925b8@syzkaller.appspotmail.com Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: syzbot+1fa947e7f09e136925b8@syzkaller.appspotmail.com Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
3164 lines
83 KiB
C
3164 lines
83 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/buffer.c
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*
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* Copyright (C) 1991, 1992, 2002 Linus Torvalds
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*/
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/*
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* Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
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*
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* Removed a lot of unnecessary code and simplified things now that
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* the buffer cache isn't our primary cache - Andrew Tridgell 12/96
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*
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* Speed up hash, lru, and free list operations. Use gfp() for allocating
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* hash table, use SLAB cache for buffer heads. SMP threading. -DaveM
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*
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* Added 32k buffer block sizes - these are required older ARM systems. - RMK
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*
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* async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
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*/
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#include <linux/kernel.h>
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#include <linux/sched/signal.h>
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#include <linux/syscalls.h>
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#include <linux/fs.h>
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#include <linux/iomap.h>
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#include <linux/mm.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/capability.h>
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#include <linux/blkdev.h>
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#include <linux/file.h>
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#include <linux/quotaops.h>
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#include <linux/highmem.h>
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#include <linux/export.h>
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#include <linux/backing-dev.h>
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#include <linux/writeback.h>
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#include <linux/hash.h>
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#include <linux/suspend.h>
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#include <linux/buffer_head.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/bio.h>
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#include <linux/cpu.h>
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#include <linux/bitops.h>
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#include <linux/mpage.h>
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#include <linux/bit_spinlock.h>
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#include <linux/pagevec.h>
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#include <linux/sched/mm.h>
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#include <trace/events/block.h>
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#include <linux/fscrypt.h>
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#include <linux/fsverity.h>
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#include <linux/sched/isolation.h>
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#include "internal.h"
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static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
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static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
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struct writeback_control *wbc);
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#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
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inline void touch_buffer(struct buffer_head *bh)
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{
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trace_block_touch_buffer(bh);
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folio_mark_accessed(bh->b_folio);
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}
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EXPORT_SYMBOL(touch_buffer);
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void __lock_buffer(struct buffer_head *bh)
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{
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wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(__lock_buffer);
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void unlock_buffer(struct buffer_head *bh)
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{
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clear_bit_unlock(BH_Lock, &bh->b_state);
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smp_mb__after_atomic();
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wake_up_bit(&bh->b_state, BH_Lock);
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}
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EXPORT_SYMBOL(unlock_buffer);
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/*
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* Returns if the folio has dirty or writeback buffers. If all the buffers
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* are unlocked and clean then the folio_test_dirty information is stale. If
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* any of the buffers are locked, it is assumed they are locked for IO.
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*/
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void buffer_check_dirty_writeback(struct folio *folio,
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bool *dirty, bool *writeback)
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{
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struct buffer_head *head, *bh;
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*dirty = false;
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*writeback = false;
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BUG_ON(!folio_test_locked(folio));
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head = folio_buffers(folio);
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if (!head)
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return;
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if (folio_test_writeback(folio))
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*writeback = true;
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bh = head;
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do {
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if (buffer_locked(bh))
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*writeback = true;
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if (buffer_dirty(bh))
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*dirty = true;
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bh = bh->b_this_page;
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} while (bh != head);
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}
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/*
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* Block until a buffer comes unlocked. This doesn't stop it
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* from becoming locked again - you have to lock it yourself
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* if you want to preserve its state.
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*/
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void __wait_on_buffer(struct buffer_head * bh)
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{
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wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(__wait_on_buffer);
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static void buffer_io_error(struct buffer_head *bh, char *msg)
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{
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if (!test_bit(BH_Quiet, &bh->b_state))
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printk_ratelimited(KERN_ERR
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"Buffer I/O error on dev %pg, logical block %llu%s\n",
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bh->b_bdev, (unsigned long long)bh->b_blocknr, msg);
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}
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/*
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* End-of-IO handler helper function which does not touch the bh after
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* unlocking it.
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* Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
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* a race there is benign: unlock_buffer() only use the bh's address for
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* hashing after unlocking the buffer, so it doesn't actually touch the bh
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* itself.
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*/
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static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
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{
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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/* This happens, due to failed read-ahead attempts. */
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clear_buffer_uptodate(bh);
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}
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unlock_buffer(bh);
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}
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/*
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* Default synchronous end-of-IO handler.. Just mark it up-to-date and
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* unlock the buffer.
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*/
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void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
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{
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__end_buffer_read_notouch(bh, uptodate);
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put_bh(bh);
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}
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EXPORT_SYMBOL(end_buffer_read_sync);
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void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
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{
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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buffer_io_error(bh, ", lost sync page write");
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mark_buffer_write_io_error(bh);
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clear_buffer_uptodate(bh);
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}
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unlock_buffer(bh);
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put_bh(bh);
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}
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EXPORT_SYMBOL(end_buffer_write_sync);
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/*
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* Various filesystems appear to want __find_get_block to be non-blocking.
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* But it's the page lock which protects the buffers. To get around this,
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* we get exclusion from try_to_free_buffers with the blockdev mapping's
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* private_lock.
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*
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* Hack idea: for the blockdev mapping, private_lock contention
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* may be quite high. This code could TryLock the page, and if that
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* succeeds, there is no need to take private_lock.
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*/
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static struct buffer_head *
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__find_get_block_slow(struct block_device *bdev, sector_t block)
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{
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struct inode *bd_inode = bdev->bd_inode;
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struct address_space *bd_mapping = bd_inode->i_mapping;
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struct buffer_head *ret = NULL;
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pgoff_t index;
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struct buffer_head *bh;
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struct buffer_head *head;
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struct folio *folio;
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int all_mapped = 1;
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static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1);
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index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
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folio = __filemap_get_folio(bd_mapping, index, FGP_ACCESSED, 0);
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if (IS_ERR(folio))
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goto out;
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spin_lock(&bd_mapping->private_lock);
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head = folio_buffers(folio);
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if (!head)
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goto out_unlock;
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bh = head;
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do {
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if (!buffer_mapped(bh))
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all_mapped = 0;
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else if (bh->b_blocknr == block) {
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ret = bh;
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get_bh(bh);
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goto out_unlock;
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}
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bh = bh->b_this_page;
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} while (bh != head);
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/* we might be here because some of the buffers on this page are
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* not mapped. This is due to various races between
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* file io on the block device and getblk. It gets dealt with
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* elsewhere, don't buffer_error if we had some unmapped buffers
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*/
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ratelimit_set_flags(&last_warned, RATELIMIT_MSG_ON_RELEASE);
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if (all_mapped && __ratelimit(&last_warned)) {
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printk("__find_get_block_slow() failed. block=%llu, "
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"b_blocknr=%llu, b_state=0x%08lx, b_size=%zu, "
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"device %pg blocksize: %d\n",
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(unsigned long long)block,
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(unsigned long long)bh->b_blocknr,
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bh->b_state, bh->b_size, bdev,
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1 << bd_inode->i_blkbits);
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}
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out_unlock:
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spin_unlock(&bd_mapping->private_lock);
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folio_put(folio);
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out:
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return ret;
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}
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static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
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{
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unsigned long flags;
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struct buffer_head *first;
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struct buffer_head *tmp;
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struct folio *folio;
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int folio_uptodate = 1;
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BUG_ON(!buffer_async_read(bh));
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folio = bh->b_folio;
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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clear_buffer_uptodate(bh);
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buffer_io_error(bh, ", async page read");
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folio_set_error(folio);
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}
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/*
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* Be _very_ careful from here on. Bad things can happen if
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* two buffer heads end IO at almost the same time and both
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* decide that the page is now completely done.
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*/
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first = folio_buffers(folio);
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spin_lock_irqsave(&first->b_uptodate_lock, flags);
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clear_buffer_async_read(bh);
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unlock_buffer(bh);
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tmp = bh;
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do {
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if (!buffer_uptodate(tmp))
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folio_uptodate = 0;
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if (buffer_async_read(tmp)) {
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BUG_ON(!buffer_locked(tmp));
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goto still_busy;
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}
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tmp = tmp->b_this_page;
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} while (tmp != bh);
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
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/*
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* If all of the buffers are uptodate then we can set the page
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* uptodate.
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*/
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if (folio_uptodate)
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folio_mark_uptodate(folio);
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folio_unlock(folio);
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return;
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still_busy:
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
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return;
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}
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struct postprocess_bh_ctx {
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struct work_struct work;
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struct buffer_head *bh;
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};
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static void verify_bh(struct work_struct *work)
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{
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struct postprocess_bh_ctx *ctx =
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container_of(work, struct postprocess_bh_ctx, work);
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struct buffer_head *bh = ctx->bh;
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bool valid;
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valid = fsverity_verify_blocks(bh->b_folio, bh->b_size, bh_offset(bh));
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end_buffer_async_read(bh, valid);
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kfree(ctx);
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}
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static bool need_fsverity(struct buffer_head *bh)
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{
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struct folio *folio = bh->b_folio;
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struct inode *inode = folio->mapping->host;
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return fsverity_active(inode) &&
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/* needed by ext4 */
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folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
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}
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static void decrypt_bh(struct work_struct *work)
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{
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struct postprocess_bh_ctx *ctx =
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container_of(work, struct postprocess_bh_ctx, work);
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struct buffer_head *bh = ctx->bh;
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int err;
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err = fscrypt_decrypt_pagecache_blocks(bh->b_folio, bh->b_size,
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bh_offset(bh));
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if (err == 0 && need_fsverity(bh)) {
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/*
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* We use different work queues for decryption and for verity
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* because verity may require reading metadata pages that need
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* decryption, and we shouldn't recurse to the same workqueue.
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*/
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INIT_WORK(&ctx->work, verify_bh);
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fsverity_enqueue_verify_work(&ctx->work);
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return;
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}
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end_buffer_async_read(bh, err == 0);
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kfree(ctx);
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}
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/*
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* I/O completion handler for block_read_full_folio() - pages
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* which come unlocked at the end of I/O.
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*/
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static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
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{
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struct inode *inode = bh->b_folio->mapping->host;
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bool decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
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bool verify = need_fsverity(bh);
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/* Decrypt (with fscrypt) and/or verify (with fsverity) if needed. */
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if (uptodate && (decrypt || verify)) {
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struct postprocess_bh_ctx *ctx =
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kmalloc(sizeof(*ctx), GFP_ATOMIC);
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if (ctx) {
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ctx->bh = bh;
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if (decrypt) {
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INIT_WORK(&ctx->work, decrypt_bh);
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fscrypt_enqueue_decrypt_work(&ctx->work);
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} else {
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INIT_WORK(&ctx->work, verify_bh);
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fsverity_enqueue_verify_work(&ctx->work);
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}
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return;
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}
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uptodate = 0;
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}
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end_buffer_async_read(bh, uptodate);
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}
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/*
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* Completion handler for block_write_full_page() - pages which are unlocked
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* during I/O, and which have PageWriteback cleared upon I/O completion.
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*/
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void end_buffer_async_write(struct buffer_head *bh, int uptodate)
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{
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unsigned long flags;
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struct buffer_head *first;
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struct buffer_head *tmp;
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struct folio *folio;
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BUG_ON(!buffer_async_write(bh));
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folio = bh->b_folio;
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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buffer_io_error(bh, ", lost async page write");
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mark_buffer_write_io_error(bh);
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clear_buffer_uptodate(bh);
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folio_set_error(folio);
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}
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first = folio_buffers(folio);
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spin_lock_irqsave(&first->b_uptodate_lock, flags);
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clear_buffer_async_write(bh);
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unlock_buffer(bh);
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tmp = bh->b_this_page;
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while (tmp != bh) {
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if (buffer_async_write(tmp)) {
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BUG_ON(!buffer_locked(tmp));
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goto still_busy;
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}
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tmp = tmp->b_this_page;
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}
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
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folio_end_writeback(folio);
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return;
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still_busy:
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
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return;
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}
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EXPORT_SYMBOL(end_buffer_async_write);
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|
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/*
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* If a page's buffers are under async readin (end_buffer_async_read
|
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* completion) then there is a possibility that another thread of
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* control could lock one of the buffers after it has completed
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* but while some of the other buffers have not completed. This
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* locked buffer would confuse end_buffer_async_read() into not unlocking
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* the page. So the absence of BH_Async_Read tells end_buffer_async_read()
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* that this buffer is not under async I/O.
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*
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* The page comes unlocked when it has no locked buffer_async buffers
|
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* left.
|
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*
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* PageLocked prevents anyone starting new async I/O reads any of
|
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* the buffers.
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*
|
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* PageWriteback is used to prevent simultaneous writeout of the same
|
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* page.
|
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*
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* PageLocked prevents anyone from starting writeback of a page which is
|
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* under read I/O (PageWriteback is only ever set against a locked page).
|
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*/
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static void mark_buffer_async_read(struct buffer_head *bh)
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{
|
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bh->b_end_io = end_buffer_async_read_io;
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set_buffer_async_read(bh);
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}
|
|
|
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static void mark_buffer_async_write_endio(struct buffer_head *bh,
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bh_end_io_t *handler)
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{
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bh->b_end_io = handler;
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set_buffer_async_write(bh);
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}
|
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|
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void mark_buffer_async_write(struct buffer_head *bh)
|
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{
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mark_buffer_async_write_endio(bh, end_buffer_async_write);
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}
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EXPORT_SYMBOL(mark_buffer_async_write);
|
|
|
|
|
|
/*
|
|
* fs/buffer.c contains helper functions for buffer-backed address space's
|
|
* fsync functions. A common requirement for buffer-based filesystems is
|
|
* that certain data from the backing blockdev needs to be written out for
|
|
* a successful fsync(). For example, ext2 indirect blocks need to be
|
|
* written back and waited upon before fsync() returns.
|
|
*
|
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* The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
|
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* inode_has_buffers() and invalidate_inode_buffers() are provided for the
|
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* management of a list of dependent buffers at ->i_mapping->private_list.
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*
|
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* Locking is a little subtle: try_to_free_buffers() will remove buffers
|
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* from their controlling inode's queue when they are being freed. But
|
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* try_to_free_buffers() will be operating against the *blockdev* mapping
|
|
* at the time, not against the S_ISREG file which depends on those buffers.
|
|
* So the locking for private_list is via the private_lock in the address_space
|
|
* which backs the buffers. Which is different from the address_space
|
|
* against which the buffers are listed. So for a particular address_space,
|
|
* mapping->private_lock does *not* protect mapping->private_list! In fact,
|
|
* mapping->private_list will always be protected by the backing blockdev's
|
|
* ->private_lock.
|
|
*
|
|
* Which introduces a requirement: all buffers on an address_space's
|
|
* ->private_list must be from the same address_space: the blockdev's.
|
|
*
|
|
* address_spaces which do not place buffers at ->private_list via these
|
|
* utility functions are free to use private_lock and private_list for
|
|
* whatever they want. The only requirement is that list_empty(private_list)
|
|
* be true at clear_inode() time.
|
|
*
|
|
* FIXME: clear_inode should not call invalidate_inode_buffers(). The
|
|
* filesystems should do that. invalidate_inode_buffers() should just go
|
|
* BUG_ON(!list_empty).
|
|
*
|
|
* FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
|
|
* take an address_space, not an inode. And it should be called
|
|
* mark_buffer_dirty_fsync() to clearly define why those buffers are being
|
|
* queued up.
|
|
*
|
|
* FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
|
|
* list if it is already on a list. Because if the buffer is on a list,
|
|
* it *must* already be on the right one. If not, the filesystem is being
|
|
* silly. This will save a ton of locking. But first we have to ensure
|
|
* that buffers are taken *off* the old inode's list when they are freed
|
|
* (presumably in truncate). That requires careful auditing of all
|
|
* filesystems (do it inside bforget()). It could also be done by bringing
|
|
* b_inode back.
|
|
*/
|
|
|
|
/*
|
|
* The buffer's backing address_space's private_lock must be held
|
|
*/
|
|
static void __remove_assoc_queue(struct buffer_head *bh)
|
|
{
|
|
list_del_init(&bh->b_assoc_buffers);
|
|
WARN_ON(!bh->b_assoc_map);
|
|
bh->b_assoc_map = NULL;
|
|
}
|
|
|
|
int inode_has_buffers(struct inode *inode)
|
|
{
|
|
return !list_empty(&inode->i_data.private_list);
|
|
}
|
|
|
|
/*
|
|
* osync is designed to support O_SYNC io. It waits synchronously for
|
|
* all already-submitted IO to complete, but does not queue any new
|
|
* writes to the disk.
|
|
*
|
|
* To do O_SYNC writes, just queue the buffer writes with write_dirty_buffer
|
|
* as you dirty the buffers, and then use osync_inode_buffers to wait for
|
|
* completion. Any other dirty buffers which are not yet queued for
|
|
* write will not be flushed to disk by the osync.
|
|
*/
|
|
static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
|
|
{
|
|
struct buffer_head *bh;
|
|
struct list_head *p;
|
|
int err = 0;
|
|
|
|
spin_lock(lock);
|
|
repeat:
|
|
list_for_each_prev(p, list) {
|
|
bh = BH_ENTRY(p);
|
|
if (buffer_locked(bh)) {
|
|
get_bh(bh);
|
|
spin_unlock(lock);
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
err = -EIO;
|
|
brelse(bh);
|
|
spin_lock(lock);
|
|
goto repeat;
|
|
}
|
|
}
|
|
spin_unlock(lock);
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
|
|
* @mapping: the mapping which wants those buffers written
|
|
*
|
|
* Starts I/O against the buffers at mapping->private_list, and waits upon
|
|
* that I/O.
|
|
*
|
|
* Basically, this is a convenience function for fsync().
|
|
* @mapping is a file or directory which needs those buffers to be written for
|
|
* a successful fsync().
|
|
*/
|
|
int sync_mapping_buffers(struct address_space *mapping)
|
|
{
|
|
struct address_space *buffer_mapping = mapping->private_data;
|
|
|
|
if (buffer_mapping == NULL || list_empty(&mapping->private_list))
|
|
return 0;
|
|
|
|
return fsync_buffers_list(&buffer_mapping->private_lock,
|
|
&mapping->private_list);
|
|
}
|
|
EXPORT_SYMBOL(sync_mapping_buffers);
|
|
|
|
/**
|
|
* generic_buffers_fsync_noflush - generic buffer fsync implementation
|
|
* for simple filesystems with no inode lock
|
|
*
|
|
* @file: file to synchronize
|
|
* @start: start offset in bytes
|
|
* @end: end offset in bytes (inclusive)
|
|
* @datasync: only synchronize essential metadata if true
|
|
*
|
|
* This is a generic implementation of the fsync method for simple
|
|
* filesystems which track all non-inode metadata in the buffers list
|
|
* hanging off the address_space structure.
|
|
*/
|
|
int generic_buffers_fsync_noflush(struct file *file, loff_t start, loff_t end,
|
|
bool datasync)
|
|
{
|
|
struct inode *inode = file->f_mapping->host;
|
|
int err;
|
|
int ret;
|
|
|
|
err = file_write_and_wait_range(file, start, end);
|
|
if (err)
|
|
return err;
|
|
|
|
ret = sync_mapping_buffers(inode->i_mapping);
|
|
if (!(inode->i_state & I_DIRTY_ALL))
|
|
goto out;
|
|
if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
|
|
goto out;
|
|
|
|
err = sync_inode_metadata(inode, 1);
|
|
if (ret == 0)
|
|
ret = err;
|
|
|
|
out:
|
|
/* check and advance again to catch errors after syncing out buffers */
|
|
err = file_check_and_advance_wb_err(file);
|
|
if (ret == 0)
|
|
ret = err;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(generic_buffers_fsync_noflush);
|
|
|
|
/**
|
|
* generic_buffers_fsync - generic buffer fsync implementation
|
|
* for simple filesystems with no inode lock
|
|
*
|
|
* @file: file to synchronize
|
|
* @start: start offset in bytes
|
|
* @end: end offset in bytes (inclusive)
|
|
* @datasync: only synchronize essential metadata if true
|
|
*
|
|
* This is a generic implementation of the fsync method for simple
|
|
* filesystems which track all non-inode metadata in the buffers list
|
|
* hanging off the address_space structure. This also makes sure that
|
|
* a device cache flush operation is called at the end.
|
|
*/
|
|
int generic_buffers_fsync(struct file *file, loff_t start, loff_t end,
|
|
bool datasync)
|
|
{
|
|
struct inode *inode = file->f_mapping->host;
|
|
int ret;
|
|
|
|
ret = generic_buffers_fsync_noflush(file, start, end, datasync);
|
|
if (!ret)
|
|
ret = blkdev_issue_flush(inode->i_sb->s_bdev);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(generic_buffers_fsync);
|
|
|
|
/*
|
|
* Called when we've recently written block `bblock', and it is known that
|
|
* `bblock' was for a buffer_boundary() buffer. This means that the block at
|
|
* `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
|
|
* dirty, schedule it for IO. So that indirects merge nicely with their data.
|
|
*/
|
|
void write_boundary_block(struct block_device *bdev,
|
|
sector_t bblock, unsigned blocksize)
|
|
{
|
|
struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
|
|
if (bh) {
|
|
if (buffer_dirty(bh))
|
|
write_dirty_buffer(bh, 0);
|
|
put_bh(bh);
|
|
}
|
|
}
|
|
|
|
void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct address_space *buffer_mapping = bh->b_folio->mapping;
|
|
|
|
mark_buffer_dirty(bh);
|
|
if (!mapping->private_data) {
|
|
mapping->private_data = buffer_mapping;
|
|
} else {
|
|
BUG_ON(mapping->private_data != buffer_mapping);
|
|
}
|
|
if (!bh->b_assoc_map) {
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
list_move_tail(&bh->b_assoc_buffers,
|
|
&mapping->private_list);
|
|
bh->b_assoc_map = mapping;
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_dirty_inode);
|
|
|
|
/*
|
|
* Add a page to the dirty page list.
|
|
*
|
|
* It is a sad fact of life that this function is called from several places
|
|
* deeply under spinlocking. It may not sleep.
|
|
*
|
|
* If the page has buffers, the uptodate buffers are set dirty, to preserve
|
|
* dirty-state coherency between the page and the buffers. It the page does
|
|
* not have buffers then when they are later attached they will all be set
|
|
* dirty.
|
|
*
|
|
* The buffers are dirtied before the page is dirtied. There's a small race
|
|
* window in which a writepage caller may see the page cleanness but not the
|
|
* buffer dirtiness. That's fine. If this code were to set the page dirty
|
|
* before the buffers, a concurrent writepage caller could clear the page dirty
|
|
* bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
|
|
* page on the dirty page list.
|
|
*
|
|
* We use private_lock to lock against try_to_free_buffers while using the
|
|
* page's buffer list. Also use this to protect against clean buffers being
|
|
* added to the page after it was set dirty.
|
|
*
|
|
* FIXME: may need to call ->reservepage here as well. That's rather up to the
|
|
* address_space though.
|
|
*/
|
|
bool block_dirty_folio(struct address_space *mapping, struct folio *folio)
|
|
{
|
|
struct buffer_head *head;
|
|
bool newly_dirty;
|
|
|
|
spin_lock(&mapping->private_lock);
|
|
head = folio_buffers(folio);
|
|
if (head) {
|
|
struct buffer_head *bh = head;
|
|
|
|
do {
|
|
set_buffer_dirty(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
}
|
|
/*
|
|
* Lock out page's memcg migration to keep PageDirty
|
|
* synchronized with per-memcg dirty page counters.
|
|
*/
|
|
folio_memcg_lock(folio);
|
|
newly_dirty = !folio_test_set_dirty(folio);
|
|
spin_unlock(&mapping->private_lock);
|
|
|
|
if (newly_dirty)
|
|
__folio_mark_dirty(folio, mapping, 1);
|
|
|
|
folio_memcg_unlock(folio);
|
|
|
|
if (newly_dirty)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
|
|
return newly_dirty;
|
|
}
|
|
EXPORT_SYMBOL(block_dirty_folio);
|
|
|
|
/*
|
|
* Write out and wait upon a list of buffers.
|
|
*
|
|
* We have conflicting pressures: we want to make sure that all
|
|
* initially dirty buffers get waited on, but that any subsequently
|
|
* dirtied buffers don't. After all, we don't want fsync to last
|
|
* forever if somebody is actively writing to the file.
|
|
*
|
|
* Do this in two main stages: first we copy dirty buffers to a
|
|
* temporary inode list, queueing the writes as we go. Then we clean
|
|
* up, waiting for those writes to complete.
|
|
*
|
|
* During this second stage, any subsequent updates to the file may end
|
|
* up refiling the buffer on the original inode's dirty list again, so
|
|
* there is a chance we will end up with a buffer queued for write but
|
|
* not yet completed on that list. So, as a final cleanup we go through
|
|
* the osync code to catch these locked, dirty buffers without requeuing
|
|
* any newly dirty buffers for write.
|
|
*/
|
|
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
|
|
{
|
|
struct buffer_head *bh;
|
|
struct list_head tmp;
|
|
struct address_space *mapping;
|
|
int err = 0, err2;
|
|
struct blk_plug plug;
|
|
|
|
INIT_LIST_HEAD(&tmp);
|
|
blk_start_plug(&plug);
|
|
|
|
spin_lock(lock);
|
|
while (!list_empty(list)) {
|
|
bh = BH_ENTRY(list->next);
|
|
mapping = bh->b_assoc_map;
|
|
__remove_assoc_queue(bh);
|
|
/* Avoid race with mark_buffer_dirty_inode() which does
|
|
* a lockless check and we rely on seeing the dirty bit */
|
|
smp_mb();
|
|
if (buffer_dirty(bh) || buffer_locked(bh)) {
|
|
list_add(&bh->b_assoc_buffers, &tmp);
|
|
bh->b_assoc_map = mapping;
|
|
if (buffer_dirty(bh)) {
|
|
get_bh(bh);
|
|
spin_unlock(lock);
|
|
/*
|
|
* Ensure any pending I/O completes so that
|
|
* write_dirty_buffer() actually writes the
|
|
* current contents - it is a noop if I/O is
|
|
* still in flight on potentially older
|
|
* contents.
|
|
*/
|
|
write_dirty_buffer(bh, REQ_SYNC);
|
|
|
|
/*
|
|
* Kick off IO for the previous mapping. Note
|
|
* that we will not run the very last mapping,
|
|
* wait_on_buffer() will do that for us
|
|
* through sync_buffer().
|
|
*/
|
|
brelse(bh);
|
|
spin_lock(lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
spin_unlock(lock);
|
|
blk_finish_plug(&plug);
|
|
spin_lock(lock);
|
|
|
|
while (!list_empty(&tmp)) {
|
|
bh = BH_ENTRY(tmp.prev);
|
|
get_bh(bh);
|
|
mapping = bh->b_assoc_map;
|
|
__remove_assoc_queue(bh);
|
|
/* Avoid race with mark_buffer_dirty_inode() which does
|
|
* a lockless check and we rely on seeing the dirty bit */
|
|
smp_mb();
|
|
if (buffer_dirty(bh)) {
|
|
list_add(&bh->b_assoc_buffers,
|
|
&mapping->private_list);
|
|
bh->b_assoc_map = mapping;
|
|
}
|
|
spin_unlock(lock);
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
err = -EIO;
|
|
brelse(bh);
|
|
spin_lock(lock);
|
|
}
|
|
|
|
spin_unlock(lock);
|
|
err2 = osync_buffers_list(lock, list);
|
|
if (err)
|
|
return err;
|
|
else
|
|
return err2;
|
|
}
|
|
|
|
/*
|
|
* Invalidate any and all dirty buffers on a given inode. We are
|
|
* probably unmounting the fs, but that doesn't mean we have already
|
|
* done a sync(). Just drop the buffers from the inode list.
|
|
*
|
|
* NOTE: we take the inode's blockdev's mapping's private_lock. Which
|
|
* assumes that all the buffers are against the blockdev. Not true
|
|
* for reiserfs.
|
|
*/
|
|
void invalidate_inode_buffers(struct inode *inode)
|
|
{
|
|
if (inode_has_buffers(inode)) {
|
|
struct address_space *mapping = &inode->i_data;
|
|
struct list_head *list = &mapping->private_list;
|
|
struct address_space *buffer_mapping = mapping->private_data;
|
|
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
while (!list_empty(list))
|
|
__remove_assoc_queue(BH_ENTRY(list->next));
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(invalidate_inode_buffers);
|
|
|
|
/*
|
|
* Remove any clean buffers from the inode's buffer list. This is called
|
|
* when we're trying to free the inode itself. Those buffers can pin it.
|
|
*
|
|
* Returns true if all buffers were removed.
|
|
*/
|
|
int remove_inode_buffers(struct inode *inode)
|
|
{
|
|
int ret = 1;
|
|
|
|
if (inode_has_buffers(inode)) {
|
|
struct address_space *mapping = &inode->i_data;
|
|
struct list_head *list = &mapping->private_list;
|
|
struct address_space *buffer_mapping = mapping->private_data;
|
|
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
while (!list_empty(list)) {
|
|
struct buffer_head *bh = BH_ENTRY(list->next);
|
|
if (buffer_dirty(bh)) {
|
|
ret = 0;
|
|
break;
|
|
}
|
|
__remove_assoc_queue(bh);
|
|
}
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Create the appropriate buffers when given a folio for data area and
|
|
* the size of each buffer.. Use the bh->b_this_page linked list to
|
|
* follow the buffers created. Return NULL if unable to create more
|
|
* buffers.
|
|
*
|
|
* The retry flag is used to differentiate async IO (paging, swapping)
|
|
* which may not fail from ordinary buffer allocations.
|
|
*/
|
|
struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
|
|
bool retry)
|
|
{
|
|
struct buffer_head *bh, *head;
|
|
gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT;
|
|
long offset;
|
|
struct mem_cgroup *memcg, *old_memcg;
|
|
|
|
if (retry)
|
|
gfp |= __GFP_NOFAIL;
|
|
|
|
/* The folio lock pins the memcg */
|
|
memcg = folio_memcg(folio);
|
|
old_memcg = set_active_memcg(memcg);
|
|
|
|
head = NULL;
|
|
offset = folio_size(folio);
|
|
while ((offset -= size) >= 0) {
|
|
bh = alloc_buffer_head(gfp);
|
|
if (!bh)
|
|
goto no_grow;
|
|
|
|
bh->b_this_page = head;
|
|
bh->b_blocknr = -1;
|
|
head = bh;
|
|
|
|
bh->b_size = size;
|
|
|
|
/* Link the buffer to its folio */
|
|
folio_set_bh(bh, folio, offset);
|
|
}
|
|
out:
|
|
set_active_memcg(old_memcg);
|
|
return head;
|
|
/*
|
|
* In case anything failed, we just free everything we got.
|
|
*/
|
|
no_grow:
|
|
if (head) {
|
|
do {
|
|
bh = head;
|
|
head = head->b_this_page;
|
|
free_buffer_head(bh);
|
|
} while (head);
|
|
}
|
|
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL_GPL(folio_alloc_buffers);
|
|
|
|
struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
|
|
bool retry)
|
|
{
|
|
return folio_alloc_buffers(page_folio(page), size, retry);
|
|
}
|
|
EXPORT_SYMBOL_GPL(alloc_page_buffers);
|
|
|
|
static inline void link_dev_buffers(struct folio *folio,
|
|
struct buffer_head *head)
|
|
{
|
|
struct buffer_head *bh, *tail;
|
|
|
|
bh = head;
|
|
do {
|
|
tail = bh;
|
|
bh = bh->b_this_page;
|
|
} while (bh);
|
|
tail->b_this_page = head;
|
|
folio_attach_private(folio, head);
|
|
}
|
|
|
|
static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
|
|
{
|
|
sector_t retval = ~((sector_t)0);
|
|
loff_t sz = bdev_nr_bytes(bdev);
|
|
|
|
if (sz) {
|
|
unsigned int sizebits = blksize_bits(size);
|
|
retval = (sz >> sizebits);
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* Initialise the state of a blockdev folio's buffers.
|
|
*/
|
|
static sector_t folio_init_buffers(struct folio *folio,
|
|
struct block_device *bdev, sector_t block, int size)
|
|
{
|
|
struct buffer_head *head = folio_buffers(folio);
|
|
struct buffer_head *bh = head;
|
|
bool uptodate = folio_test_uptodate(folio);
|
|
sector_t end_block = blkdev_max_block(bdev, size);
|
|
|
|
do {
|
|
if (!buffer_mapped(bh)) {
|
|
bh->b_end_io = NULL;
|
|
bh->b_private = NULL;
|
|
bh->b_bdev = bdev;
|
|
bh->b_blocknr = block;
|
|
if (uptodate)
|
|
set_buffer_uptodate(bh);
|
|
if (block < end_block)
|
|
set_buffer_mapped(bh);
|
|
}
|
|
block++;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* Caller needs to validate requested block against end of device.
|
|
*/
|
|
return end_block;
|
|
}
|
|
|
|
/*
|
|
* Create the page-cache page that contains the requested block.
|
|
*
|
|
* This is used purely for blockdev mappings.
|
|
*/
|
|
static int
|
|
grow_dev_page(struct block_device *bdev, sector_t block,
|
|
pgoff_t index, int size, int sizebits, gfp_t gfp)
|
|
{
|
|
struct inode *inode = bdev->bd_inode;
|
|
struct folio *folio;
|
|
struct buffer_head *bh;
|
|
sector_t end_block;
|
|
int ret = 0;
|
|
gfp_t gfp_mask;
|
|
|
|
gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp;
|
|
|
|
/*
|
|
* XXX: __getblk_slow() can not really deal with failure and
|
|
* will endlessly loop on improvised global reclaim. Prefer
|
|
* looping in the allocator rather than here, at least that
|
|
* code knows what it's doing.
|
|
*/
|
|
gfp_mask |= __GFP_NOFAIL;
|
|
|
|
folio = __filemap_get_folio(inode->i_mapping, index,
|
|
FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp_mask);
|
|
|
|
bh = folio_buffers(folio);
|
|
if (bh) {
|
|
if (bh->b_size == size) {
|
|
end_block = folio_init_buffers(folio, bdev,
|
|
(sector_t)index << sizebits, size);
|
|
goto done;
|
|
}
|
|
if (!try_to_free_buffers(folio))
|
|
goto failed;
|
|
}
|
|
|
|
bh = folio_alloc_buffers(folio, size, true);
|
|
|
|
/*
|
|
* Link the folio to the buffers and initialise them. Take the
|
|
* lock to be atomic wrt __find_get_block(), which does not
|
|
* run under the folio lock.
|
|
*/
|
|
spin_lock(&inode->i_mapping->private_lock);
|
|
link_dev_buffers(folio, bh);
|
|
end_block = folio_init_buffers(folio, bdev,
|
|
(sector_t)index << sizebits, size);
|
|
spin_unlock(&inode->i_mapping->private_lock);
|
|
done:
|
|
ret = (block < end_block) ? 1 : -ENXIO;
|
|
failed:
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Create buffers for the specified block device block's page. If
|
|
* that page was dirty, the buffers are set dirty also.
|
|
*/
|
|
static int
|
|
grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
|
|
{
|
|
pgoff_t index;
|
|
int sizebits;
|
|
|
|
sizebits = PAGE_SHIFT - __ffs(size);
|
|
index = block >> sizebits;
|
|
|
|
/*
|
|
* Check for a block which wants to lie outside our maximum possible
|
|
* pagecache index. (this comparison is done using sector_t types).
|
|
*/
|
|
if (unlikely(index != block >> sizebits)) {
|
|
printk(KERN_ERR "%s: requested out-of-range block %llu for "
|
|
"device %pg\n",
|
|
__func__, (unsigned long long)block,
|
|
bdev);
|
|
return -EIO;
|
|
}
|
|
|
|
/* Create a page with the proper size buffers.. */
|
|
return grow_dev_page(bdev, block, index, size, sizebits, gfp);
|
|
}
|
|
|
|
static struct buffer_head *
|
|
__getblk_slow(struct block_device *bdev, sector_t block,
|
|
unsigned size, gfp_t gfp)
|
|
{
|
|
/* Size must be multiple of hard sectorsize */
|
|
if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
|
|
(size < 512 || size > PAGE_SIZE))) {
|
|
printk(KERN_ERR "getblk(): invalid block size %d requested\n",
|
|
size);
|
|
printk(KERN_ERR "logical block size: %d\n",
|
|
bdev_logical_block_size(bdev));
|
|
|
|
dump_stack();
|
|
return NULL;
|
|
}
|
|
|
|
for (;;) {
|
|
struct buffer_head *bh;
|
|
int ret;
|
|
|
|
bh = __find_get_block(bdev, block, size);
|
|
if (bh)
|
|
return bh;
|
|
|
|
ret = grow_buffers(bdev, block, size, gfp);
|
|
if (ret < 0)
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The relationship between dirty buffers and dirty pages:
|
|
*
|
|
* Whenever a page has any dirty buffers, the page's dirty bit is set, and
|
|
* the page is tagged dirty in the page cache.
|
|
*
|
|
* At all times, the dirtiness of the buffers represents the dirtiness of
|
|
* subsections of the page. If the page has buffers, the page dirty bit is
|
|
* merely a hint about the true dirty state.
|
|
*
|
|
* When a page is set dirty in its entirety, all its buffers are marked dirty
|
|
* (if the page has buffers).
|
|
*
|
|
* When a buffer is marked dirty, its page is dirtied, but the page's other
|
|
* buffers are not.
|
|
*
|
|
* Also. When blockdev buffers are explicitly read with bread(), they
|
|
* individually become uptodate. But their backing page remains not
|
|
* uptodate - even if all of its buffers are uptodate. A subsequent
|
|
* block_read_full_folio() against that folio will discover all the uptodate
|
|
* buffers, will set the folio uptodate and will perform no I/O.
|
|
*/
|
|
|
|
/**
|
|
* mark_buffer_dirty - mark a buffer_head as needing writeout
|
|
* @bh: the buffer_head to mark dirty
|
|
*
|
|
* mark_buffer_dirty() will set the dirty bit against the buffer, then set
|
|
* its backing page dirty, then tag the page as dirty in the page cache
|
|
* and then attach the address_space's inode to its superblock's dirty
|
|
* inode list.
|
|
*
|
|
* mark_buffer_dirty() is atomic. It takes bh->b_folio->mapping->private_lock,
|
|
* i_pages lock and mapping->host->i_lock.
|
|
*/
|
|
void mark_buffer_dirty(struct buffer_head *bh)
|
|
{
|
|
WARN_ON_ONCE(!buffer_uptodate(bh));
|
|
|
|
trace_block_dirty_buffer(bh);
|
|
|
|
/*
|
|
* Very *carefully* optimize the it-is-already-dirty case.
|
|
*
|
|
* Don't let the final "is it dirty" escape to before we
|
|
* perhaps modified the buffer.
|
|
*/
|
|
if (buffer_dirty(bh)) {
|
|
smp_mb();
|
|
if (buffer_dirty(bh))
|
|
return;
|
|
}
|
|
|
|
if (!test_set_buffer_dirty(bh)) {
|
|
struct folio *folio = bh->b_folio;
|
|
struct address_space *mapping = NULL;
|
|
|
|
folio_memcg_lock(folio);
|
|
if (!folio_test_set_dirty(folio)) {
|
|
mapping = folio->mapping;
|
|
if (mapping)
|
|
__folio_mark_dirty(folio, mapping, 0);
|
|
}
|
|
folio_memcg_unlock(folio);
|
|
if (mapping)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_dirty);
|
|
|
|
void mark_buffer_write_io_error(struct buffer_head *bh)
|
|
{
|
|
set_buffer_write_io_error(bh);
|
|
/* FIXME: do we need to set this in both places? */
|
|
if (bh->b_folio && bh->b_folio->mapping)
|
|
mapping_set_error(bh->b_folio->mapping, -EIO);
|
|
if (bh->b_assoc_map) {
|
|
mapping_set_error(bh->b_assoc_map, -EIO);
|
|
errseq_set(&bh->b_assoc_map->host->i_sb->s_wb_err, -EIO);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_write_io_error);
|
|
|
|
/*
|
|
* Decrement a buffer_head's reference count. If all buffers against a page
|
|
* have zero reference count, are clean and unlocked, and if the page is clean
|
|
* and unlocked then try_to_free_buffers() may strip the buffers from the page
|
|
* in preparation for freeing it (sometimes, rarely, buffers are removed from
|
|
* a page but it ends up not being freed, and buffers may later be reattached).
|
|
*/
|
|
void __brelse(struct buffer_head * buf)
|
|
{
|
|
if (atomic_read(&buf->b_count)) {
|
|
put_bh(buf);
|
|
return;
|
|
}
|
|
WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
|
|
}
|
|
EXPORT_SYMBOL(__brelse);
|
|
|
|
/*
|
|
* bforget() is like brelse(), except it discards any
|
|
* potentially dirty data.
|
|
*/
|
|
void __bforget(struct buffer_head *bh)
|
|
{
|
|
clear_buffer_dirty(bh);
|
|
if (bh->b_assoc_map) {
|
|
struct address_space *buffer_mapping = bh->b_folio->mapping;
|
|
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
list_del_init(&bh->b_assoc_buffers);
|
|
bh->b_assoc_map = NULL;
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
__brelse(bh);
|
|
}
|
|
EXPORT_SYMBOL(__bforget);
|
|
|
|
static struct buffer_head *__bread_slow(struct buffer_head *bh)
|
|
{
|
|
lock_buffer(bh);
|
|
if (buffer_uptodate(bh)) {
|
|
unlock_buffer(bh);
|
|
return bh;
|
|
} else {
|
|
get_bh(bh);
|
|
bh->b_end_io = end_buffer_read_sync;
|
|
submit_bh(REQ_OP_READ, bh);
|
|
wait_on_buffer(bh);
|
|
if (buffer_uptodate(bh))
|
|
return bh;
|
|
}
|
|
brelse(bh);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
|
|
* The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
|
|
* refcount elevated by one when they're in an LRU. A buffer can only appear
|
|
* once in a particular CPU's LRU. A single buffer can be present in multiple
|
|
* CPU's LRUs at the same time.
|
|
*
|
|
* This is a transparent caching front-end to sb_bread(), sb_getblk() and
|
|
* sb_find_get_block().
|
|
*
|
|
* The LRUs themselves only need locking against invalidate_bh_lrus. We use
|
|
* a local interrupt disable for that.
|
|
*/
|
|
|
|
#define BH_LRU_SIZE 16
|
|
|
|
struct bh_lru {
|
|
struct buffer_head *bhs[BH_LRU_SIZE];
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define bh_lru_lock() local_irq_disable()
|
|
#define bh_lru_unlock() local_irq_enable()
|
|
#else
|
|
#define bh_lru_lock() preempt_disable()
|
|
#define bh_lru_unlock() preempt_enable()
|
|
#endif
|
|
|
|
static inline void check_irqs_on(void)
|
|
{
|
|
#ifdef irqs_disabled
|
|
BUG_ON(irqs_disabled());
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Install a buffer_head into this cpu's LRU. If not already in the LRU, it is
|
|
* inserted at the front, and the buffer_head at the back if any is evicted.
|
|
* Or, if already in the LRU it is moved to the front.
|
|
*/
|
|
static void bh_lru_install(struct buffer_head *bh)
|
|
{
|
|
struct buffer_head *evictee = bh;
|
|
struct bh_lru *b;
|
|
int i;
|
|
|
|
check_irqs_on();
|
|
bh_lru_lock();
|
|
|
|
/*
|
|
* the refcount of buffer_head in bh_lru prevents dropping the
|
|
* attached page(i.e., try_to_free_buffers) so it could cause
|
|
* failing page migration.
|
|
* Skip putting upcoming bh into bh_lru until migration is done.
|
|
*/
|
|
if (lru_cache_disabled() || cpu_is_isolated(smp_processor_id())) {
|
|
bh_lru_unlock();
|
|
return;
|
|
}
|
|
|
|
b = this_cpu_ptr(&bh_lrus);
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
swap(evictee, b->bhs[i]);
|
|
if (evictee == bh) {
|
|
bh_lru_unlock();
|
|
return;
|
|
}
|
|
}
|
|
|
|
get_bh(bh);
|
|
bh_lru_unlock();
|
|
brelse(evictee);
|
|
}
|
|
|
|
/*
|
|
* Look up the bh in this cpu's LRU. If it's there, move it to the head.
|
|
*/
|
|
static struct buffer_head *
|
|
lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
struct buffer_head *ret = NULL;
|
|
unsigned int i;
|
|
|
|
check_irqs_on();
|
|
bh_lru_lock();
|
|
if (cpu_is_isolated(smp_processor_id())) {
|
|
bh_lru_unlock();
|
|
return NULL;
|
|
}
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
|
|
|
|
if (bh && bh->b_blocknr == block && bh->b_bdev == bdev &&
|
|
bh->b_size == size) {
|
|
if (i) {
|
|
while (i) {
|
|
__this_cpu_write(bh_lrus.bhs[i],
|
|
__this_cpu_read(bh_lrus.bhs[i - 1]));
|
|
i--;
|
|
}
|
|
__this_cpu_write(bh_lrus.bhs[0], bh);
|
|
}
|
|
get_bh(bh);
|
|
ret = bh;
|
|
break;
|
|
}
|
|
}
|
|
bh_lru_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Perform a pagecache lookup for the matching buffer. If it's there, refresh
|
|
* it in the LRU and mark it as accessed. If it is not present then return
|
|
* NULL
|
|
*/
|
|
struct buffer_head *
|
|
__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
|
|
|
|
if (bh == NULL) {
|
|
/* __find_get_block_slow will mark the page accessed */
|
|
bh = __find_get_block_slow(bdev, block);
|
|
if (bh)
|
|
bh_lru_install(bh);
|
|
} else
|
|
touch_buffer(bh);
|
|
|
|
return bh;
|
|
}
|
|
EXPORT_SYMBOL(__find_get_block);
|
|
|
|
/*
|
|
* __getblk_gfp() will locate (and, if necessary, create) the buffer_head
|
|
* which corresponds to the passed block_device, block and size. The
|
|
* returned buffer has its reference count incremented.
|
|
*
|
|
* __getblk_gfp() will lock up the machine if grow_dev_page's
|
|
* try_to_free_buffers() attempt is failing. FIXME, perhaps?
|
|
*/
|
|
struct buffer_head *
|
|
__getblk_gfp(struct block_device *bdev, sector_t block,
|
|
unsigned size, gfp_t gfp)
|
|
{
|
|
struct buffer_head *bh = __find_get_block(bdev, block, size);
|
|
|
|
might_sleep();
|
|
if (bh == NULL)
|
|
bh = __getblk_slow(bdev, block, size, gfp);
|
|
return bh;
|
|
}
|
|
EXPORT_SYMBOL(__getblk_gfp);
|
|
|
|
/*
|
|
* Do async read-ahead on a buffer..
|
|
*/
|
|
void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
struct buffer_head *bh = __getblk(bdev, block, size);
|
|
if (likely(bh)) {
|
|
bh_readahead(bh, REQ_RAHEAD);
|
|
brelse(bh);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__breadahead);
|
|
|
|
/**
|
|
* __bread_gfp() - reads a specified block and returns the bh
|
|
* @bdev: the block_device to read from
|
|
* @block: number of block
|
|
* @size: size (in bytes) to read
|
|
* @gfp: page allocation flag
|
|
*
|
|
* Reads a specified block, and returns buffer head that contains it.
|
|
* The page cache can be allocated from non-movable area
|
|
* not to prevent page migration if you set gfp to zero.
|
|
* It returns NULL if the block was unreadable.
|
|
*/
|
|
struct buffer_head *
|
|
__bread_gfp(struct block_device *bdev, sector_t block,
|
|
unsigned size, gfp_t gfp)
|
|
{
|
|
struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
|
|
|
|
if (likely(bh) && !buffer_uptodate(bh))
|
|
bh = __bread_slow(bh);
|
|
return bh;
|
|
}
|
|
EXPORT_SYMBOL(__bread_gfp);
|
|
|
|
static void __invalidate_bh_lrus(struct bh_lru *b)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
brelse(b->bhs[i]);
|
|
b->bhs[i] = NULL;
|
|
}
|
|
}
|
|
/*
|
|
* invalidate_bh_lrus() is called rarely - but not only at unmount.
|
|
* This doesn't race because it runs in each cpu either in irq
|
|
* or with preempt disabled.
|
|
*/
|
|
static void invalidate_bh_lru(void *arg)
|
|
{
|
|
struct bh_lru *b = &get_cpu_var(bh_lrus);
|
|
|
|
__invalidate_bh_lrus(b);
|
|
put_cpu_var(bh_lrus);
|
|
}
|
|
|
|
bool has_bh_in_lru(int cpu, void *dummy)
|
|
{
|
|
struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
|
|
int i;
|
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
if (b->bhs[i])
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
void invalidate_bh_lrus(void)
|
|
{
|
|
on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
|
|
|
|
/*
|
|
* It's called from workqueue context so we need a bh_lru_lock to close
|
|
* the race with preemption/irq.
|
|
*/
|
|
void invalidate_bh_lrus_cpu(void)
|
|
{
|
|
struct bh_lru *b;
|
|
|
|
bh_lru_lock();
|
|
b = this_cpu_ptr(&bh_lrus);
|
|
__invalidate_bh_lrus(b);
|
|
bh_lru_unlock();
|
|
}
|
|
|
|
void folio_set_bh(struct buffer_head *bh, struct folio *folio,
|
|
unsigned long offset)
|
|
{
|
|
bh->b_folio = folio;
|
|
BUG_ON(offset >= folio_size(folio));
|
|
if (folio_test_highmem(folio))
|
|
/*
|
|
* This catches illegal uses and preserves the offset:
|
|
*/
|
|
bh->b_data = (char *)(0 + offset);
|
|
else
|
|
bh->b_data = folio_address(folio) + offset;
|
|
}
|
|
EXPORT_SYMBOL(folio_set_bh);
|
|
|
|
/*
|
|
* Called when truncating a buffer on a page completely.
|
|
*/
|
|
|
|
/* Bits that are cleared during an invalidate */
|
|
#define BUFFER_FLAGS_DISCARD \
|
|
(1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \
|
|
1 << BH_Delay | 1 << BH_Unwritten)
|
|
|
|
static void discard_buffer(struct buffer_head * bh)
|
|
{
|
|
unsigned long b_state;
|
|
|
|
lock_buffer(bh);
|
|
clear_buffer_dirty(bh);
|
|
bh->b_bdev = NULL;
|
|
b_state = READ_ONCE(bh->b_state);
|
|
do {
|
|
} while (!try_cmpxchg(&bh->b_state, &b_state,
|
|
b_state & ~BUFFER_FLAGS_DISCARD));
|
|
unlock_buffer(bh);
|
|
}
|
|
|
|
/**
|
|
* block_invalidate_folio - Invalidate part or all of a buffer-backed folio.
|
|
* @folio: The folio which is affected.
|
|
* @offset: start of the range to invalidate
|
|
* @length: length of the range to invalidate
|
|
*
|
|
* block_invalidate_folio() is called when all or part of the folio has been
|
|
* invalidated by a truncate operation.
|
|
*
|
|
* block_invalidate_folio() does not have to release all buffers, but it must
|
|
* ensure that no dirty buffer is left outside @offset and that no I/O
|
|
* is underway against any of the blocks which are outside the truncation
|
|
* point. Because the caller is about to free (and possibly reuse) those
|
|
* blocks on-disk.
|
|
*/
|
|
void block_invalidate_folio(struct folio *folio, size_t offset, size_t length)
|
|
{
|
|
struct buffer_head *head, *bh, *next;
|
|
size_t curr_off = 0;
|
|
size_t stop = length + offset;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
|
|
/*
|
|
* Check for overflow
|
|
*/
|
|
BUG_ON(stop > folio_size(folio) || stop < length);
|
|
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
return;
|
|
|
|
bh = head;
|
|
do {
|
|
size_t next_off = curr_off + bh->b_size;
|
|
next = bh->b_this_page;
|
|
|
|
/*
|
|
* Are we still fully in range ?
|
|
*/
|
|
if (next_off > stop)
|
|
goto out;
|
|
|
|
/*
|
|
* is this block fully invalidated?
|
|
*/
|
|
if (offset <= curr_off)
|
|
discard_buffer(bh);
|
|
curr_off = next_off;
|
|
bh = next;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* We release buffers only if the entire folio is being invalidated.
|
|
* The get_block cached value has been unconditionally invalidated,
|
|
* so real IO is not possible anymore.
|
|
*/
|
|
if (length == folio_size(folio))
|
|
filemap_release_folio(folio, 0);
|
|
out:
|
|
return;
|
|
}
|
|
EXPORT_SYMBOL(block_invalidate_folio);
|
|
|
|
/*
|
|
* We attach and possibly dirty the buffers atomically wrt
|
|
* block_dirty_folio() via private_lock. try_to_free_buffers
|
|
* is already excluded via the folio lock.
|
|
*/
|
|
void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize,
|
|
unsigned long b_state)
|
|
{
|
|
struct buffer_head *bh, *head, *tail;
|
|
|
|
head = folio_alloc_buffers(folio, blocksize, true);
|
|
bh = head;
|
|
do {
|
|
bh->b_state |= b_state;
|
|
tail = bh;
|
|
bh = bh->b_this_page;
|
|
} while (bh);
|
|
tail->b_this_page = head;
|
|
|
|
spin_lock(&folio->mapping->private_lock);
|
|
if (folio_test_uptodate(folio) || folio_test_dirty(folio)) {
|
|
bh = head;
|
|
do {
|
|
if (folio_test_dirty(folio))
|
|
set_buffer_dirty(bh);
|
|
if (folio_test_uptodate(folio))
|
|
set_buffer_uptodate(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
}
|
|
folio_attach_private(folio, head);
|
|
spin_unlock(&folio->mapping->private_lock);
|
|
}
|
|
EXPORT_SYMBOL(folio_create_empty_buffers);
|
|
|
|
void create_empty_buffers(struct page *page,
|
|
unsigned long blocksize, unsigned long b_state)
|
|
{
|
|
folio_create_empty_buffers(page_folio(page), blocksize, b_state);
|
|
}
|
|
EXPORT_SYMBOL(create_empty_buffers);
|
|
|
|
/**
|
|
* clean_bdev_aliases: clean a range of buffers in block device
|
|
* @bdev: Block device to clean buffers in
|
|
* @block: Start of a range of blocks to clean
|
|
* @len: Number of blocks to clean
|
|
*
|
|
* We are taking a range of blocks for data and we don't want writeback of any
|
|
* buffer-cache aliases starting from return from this function and until the
|
|
* moment when something will explicitly mark the buffer dirty (hopefully that
|
|
* will not happen until we will free that block ;-) We don't even need to mark
|
|
* it not-uptodate - nobody can expect anything from a newly allocated buffer
|
|
* anyway. We used to use unmap_buffer() for such invalidation, but that was
|
|
* wrong. We definitely don't want to mark the alias unmapped, for example - it
|
|
* would confuse anyone who might pick it with bread() afterwards...
|
|
*
|
|
* Also.. Note that bforget() doesn't lock the buffer. So there can be
|
|
* writeout I/O going on against recently-freed buffers. We don't wait on that
|
|
* I/O in bforget() - it's more efficient to wait on the I/O only if we really
|
|
* need to. That happens here.
|
|
*/
|
|
void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len)
|
|
{
|
|
struct inode *bd_inode = bdev->bd_inode;
|
|
struct address_space *bd_mapping = bd_inode->i_mapping;
|
|
struct folio_batch fbatch;
|
|
pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
|
|
pgoff_t end;
|
|
int i, count;
|
|
struct buffer_head *bh;
|
|
struct buffer_head *head;
|
|
|
|
end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits);
|
|
folio_batch_init(&fbatch);
|
|
while (filemap_get_folios(bd_mapping, &index, end, &fbatch)) {
|
|
count = folio_batch_count(&fbatch);
|
|
for (i = 0; i < count; i++) {
|
|
struct folio *folio = fbatch.folios[i];
|
|
|
|
if (!folio_buffers(folio))
|
|
continue;
|
|
/*
|
|
* We use folio lock instead of bd_mapping->private_lock
|
|
* to pin buffers here since we can afford to sleep and
|
|
* it scales better than a global spinlock lock.
|
|
*/
|
|
folio_lock(folio);
|
|
/* Recheck when the folio is locked which pins bhs */
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
goto unlock_page;
|
|
bh = head;
|
|
do {
|
|
if (!buffer_mapped(bh) || (bh->b_blocknr < block))
|
|
goto next;
|
|
if (bh->b_blocknr >= block + len)
|
|
break;
|
|
clear_buffer_dirty(bh);
|
|
wait_on_buffer(bh);
|
|
clear_buffer_req(bh);
|
|
next:
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
unlock_page:
|
|
folio_unlock(folio);
|
|
}
|
|
folio_batch_release(&fbatch);
|
|
cond_resched();
|
|
/* End of range already reached? */
|
|
if (index > end || !index)
|
|
break;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(clean_bdev_aliases);
|
|
|
|
/*
|
|
* Size is a power-of-two in the range 512..PAGE_SIZE,
|
|
* and the case we care about most is PAGE_SIZE.
|
|
*
|
|
* So this *could* possibly be written with those
|
|
* constraints in mind (relevant mostly if some
|
|
* architecture has a slow bit-scan instruction)
|
|
*/
|
|
static inline int block_size_bits(unsigned int blocksize)
|
|
{
|
|
return ilog2(blocksize);
|
|
}
|
|
|
|
static struct buffer_head *folio_create_buffers(struct folio *folio,
|
|
struct inode *inode,
|
|
unsigned int b_state)
|
|
{
|
|
BUG_ON(!folio_test_locked(folio));
|
|
|
|
if (!folio_buffers(folio))
|
|
folio_create_empty_buffers(folio,
|
|
1 << READ_ONCE(inode->i_blkbits),
|
|
b_state);
|
|
return folio_buffers(folio);
|
|
}
|
|
|
|
/*
|
|
* NOTE! All mapped/uptodate combinations are valid:
|
|
*
|
|
* Mapped Uptodate Meaning
|
|
*
|
|
* No No "unknown" - must do get_block()
|
|
* No Yes "hole" - zero-filled
|
|
* Yes No "allocated" - allocated on disk, not read in
|
|
* Yes Yes "valid" - allocated and up-to-date in memory.
|
|
*
|
|
* "Dirty" is valid only with the last case (mapped+uptodate).
|
|
*/
|
|
|
|
/*
|
|
* While block_write_full_page is writing back the dirty buffers under
|
|
* the page lock, whoever dirtied the buffers may decide to clean them
|
|
* again at any time. We handle that by only looking at the buffer
|
|
* state inside lock_buffer().
|
|
*
|
|
* If block_write_full_page() is called for regular writeback
|
|
* (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
|
|
* locked buffer. This only can happen if someone has written the buffer
|
|
* directly, with submit_bh(). At the address_space level PageWriteback
|
|
* prevents this contention from occurring.
|
|
*
|
|
* If block_write_full_page() is called with wbc->sync_mode ==
|
|
* WB_SYNC_ALL, the writes are posted using REQ_SYNC; this
|
|
* causes the writes to be flagged as synchronous writes.
|
|
*/
|
|
int __block_write_full_folio(struct inode *inode, struct folio *folio,
|
|
get_block_t *get_block, struct writeback_control *wbc,
|
|
bh_end_io_t *handler)
|
|
{
|
|
int err;
|
|
sector_t block;
|
|
sector_t last_block;
|
|
struct buffer_head *bh, *head;
|
|
unsigned int blocksize, bbits;
|
|
int nr_underway = 0;
|
|
blk_opf_t write_flags = wbc_to_write_flags(wbc);
|
|
|
|
head = folio_create_buffers(folio, inode,
|
|
(1 << BH_Dirty) | (1 << BH_Uptodate));
|
|
|
|
/*
|
|
* Be very careful. We have no exclusion from block_dirty_folio
|
|
* here, and the (potentially unmapped) buffers may become dirty at
|
|
* any time. If a buffer becomes dirty here after we've inspected it
|
|
* then we just miss that fact, and the folio stays dirty.
|
|
*
|
|
* Buffers outside i_size may be dirtied by block_dirty_folio;
|
|
* handle that here by just cleaning them.
|
|
*/
|
|
|
|
bh = head;
|
|
blocksize = bh->b_size;
|
|
bbits = block_size_bits(blocksize);
|
|
|
|
block = (sector_t)folio->index << (PAGE_SHIFT - bbits);
|
|
last_block = (i_size_read(inode) - 1) >> bbits;
|
|
|
|
/*
|
|
* Get all the dirty buffers mapped to disk addresses and
|
|
* handle any aliases from the underlying blockdev's mapping.
|
|
*/
|
|
do {
|
|
if (block > last_block) {
|
|
/*
|
|
* mapped buffers outside i_size will occur, because
|
|
* this folio can be outside i_size when there is a
|
|
* truncate in progress.
|
|
*/
|
|
/*
|
|
* The buffer was zeroed by block_write_full_page()
|
|
*/
|
|
clear_buffer_dirty(bh);
|
|
set_buffer_uptodate(bh);
|
|
} else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
|
|
buffer_dirty(bh)) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
err = get_block(inode, block, bh, 1);
|
|
if (err)
|
|
goto recover;
|
|
clear_buffer_delay(bh);
|
|
if (buffer_new(bh)) {
|
|
/* blockdev mappings never come here */
|
|
clear_buffer_new(bh);
|
|
clean_bdev_bh_alias(bh);
|
|
}
|
|
}
|
|
bh = bh->b_this_page;
|
|
block++;
|
|
} while (bh != head);
|
|
|
|
do {
|
|
if (!buffer_mapped(bh))
|
|
continue;
|
|
/*
|
|
* If it's a fully non-blocking write attempt and we cannot
|
|
* lock the buffer then redirty the folio. Note that this can
|
|
* potentially cause a busy-wait loop from writeback threads
|
|
* and kswapd activity, but those code paths have their own
|
|
* higher-level throttling.
|
|
*/
|
|
if (wbc->sync_mode != WB_SYNC_NONE) {
|
|
lock_buffer(bh);
|
|
} else if (!trylock_buffer(bh)) {
|
|
folio_redirty_for_writepage(wbc, folio);
|
|
continue;
|
|
}
|
|
if (test_clear_buffer_dirty(bh)) {
|
|
mark_buffer_async_write_endio(bh, handler);
|
|
} else {
|
|
unlock_buffer(bh);
|
|
}
|
|
} while ((bh = bh->b_this_page) != head);
|
|
|
|
/*
|
|
* The folio and its buffers are protected by the writeback flag,
|
|
* so we can drop the bh refcounts early.
|
|
*/
|
|
BUG_ON(folio_test_writeback(folio));
|
|
folio_start_writeback(folio);
|
|
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
if (buffer_async_write(bh)) {
|
|
submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, wbc);
|
|
nr_underway++;
|
|
}
|
|
bh = next;
|
|
} while (bh != head);
|
|
folio_unlock(folio);
|
|
|
|
err = 0;
|
|
done:
|
|
if (nr_underway == 0) {
|
|
/*
|
|
* The folio was marked dirty, but the buffers were
|
|
* clean. Someone wrote them back by hand with
|
|
* write_dirty_buffer/submit_bh. A rare case.
|
|
*/
|
|
folio_end_writeback(folio);
|
|
|
|
/*
|
|
* The folio and buffer_heads can be released at any time from
|
|
* here on.
|
|
*/
|
|
}
|
|
return err;
|
|
|
|
recover:
|
|
/*
|
|
* ENOSPC, or some other error. We may already have added some
|
|
* blocks to the file, so we need to write these out to avoid
|
|
* exposing stale data.
|
|
* The folio is currently locked and not marked for writeback
|
|
*/
|
|
bh = head;
|
|
/* Recovery: lock and submit the mapped buffers */
|
|
do {
|
|
if (buffer_mapped(bh) && buffer_dirty(bh) &&
|
|
!buffer_delay(bh)) {
|
|
lock_buffer(bh);
|
|
mark_buffer_async_write_endio(bh, handler);
|
|
} else {
|
|
/*
|
|
* The buffer may have been set dirty during
|
|
* attachment to a dirty folio.
|
|
*/
|
|
clear_buffer_dirty(bh);
|
|
}
|
|
} while ((bh = bh->b_this_page) != head);
|
|
folio_set_error(folio);
|
|
BUG_ON(folio_test_writeback(folio));
|
|
mapping_set_error(folio->mapping, err);
|
|
folio_start_writeback(folio);
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
if (buffer_async_write(bh)) {
|
|
clear_buffer_dirty(bh);
|
|
submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, wbc);
|
|
nr_underway++;
|
|
}
|
|
bh = next;
|
|
} while (bh != head);
|
|
folio_unlock(folio);
|
|
goto done;
|
|
}
|
|
EXPORT_SYMBOL(__block_write_full_folio);
|
|
|
|
/*
|
|
* If a folio has any new buffers, zero them out here, and mark them uptodate
|
|
* and dirty so they'll be written out (in order to prevent uninitialised
|
|
* block data from leaking). And clear the new bit.
|
|
*/
|
|
void folio_zero_new_buffers(struct folio *folio, size_t from, size_t to)
|
|
{
|
|
size_t block_start, block_end;
|
|
struct buffer_head *head, *bh;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
return;
|
|
|
|
bh = head;
|
|
block_start = 0;
|
|
do {
|
|
block_end = block_start + bh->b_size;
|
|
|
|
if (buffer_new(bh)) {
|
|
if (block_end > from && block_start < to) {
|
|
if (!folio_test_uptodate(folio)) {
|
|
size_t start, xend;
|
|
|
|
start = max(from, block_start);
|
|
xend = min(to, block_end);
|
|
|
|
folio_zero_segment(folio, start, xend);
|
|
set_buffer_uptodate(bh);
|
|
}
|
|
|
|
clear_buffer_new(bh);
|
|
mark_buffer_dirty(bh);
|
|
}
|
|
}
|
|
|
|
block_start = block_end;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
}
|
|
EXPORT_SYMBOL(folio_zero_new_buffers);
|
|
|
|
static int
|
|
iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
|
|
const struct iomap *iomap)
|
|
{
|
|
loff_t offset = block << inode->i_blkbits;
|
|
|
|
bh->b_bdev = iomap->bdev;
|
|
|
|
/*
|
|
* Block points to offset in file we need to map, iomap contains
|
|
* the offset at which the map starts. If the map ends before the
|
|
* current block, then do not map the buffer and let the caller
|
|
* handle it.
|
|
*/
|
|
if (offset >= iomap->offset + iomap->length)
|
|
return -EIO;
|
|
|
|
switch (iomap->type) {
|
|
case IOMAP_HOLE:
|
|
/*
|
|
* If the buffer is not up to date or beyond the current EOF,
|
|
* we need to mark it as new to ensure sub-block zeroing is
|
|
* executed if necessary.
|
|
*/
|
|
if (!buffer_uptodate(bh) ||
|
|
(offset >= i_size_read(inode)))
|
|
set_buffer_new(bh);
|
|
return 0;
|
|
case IOMAP_DELALLOC:
|
|
if (!buffer_uptodate(bh) ||
|
|
(offset >= i_size_read(inode)))
|
|
set_buffer_new(bh);
|
|
set_buffer_uptodate(bh);
|
|
set_buffer_mapped(bh);
|
|
set_buffer_delay(bh);
|
|
return 0;
|
|
case IOMAP_UNWRITTEN:
|
|
/*
|
|
* For unwritten regions, we always need to ensure that regions
|
|
* in the block we are not writing to are zeroed. Mark the
|
|
* buffer as new to ensure this.
|
|
*/
|
|
set_buffer_new(bh);
|
|
set_buffer_unwritten(bh);
|
|
fallthrough;
|
|
case IOMAP_MAPPED:
|
|
if ((iomap->flags & IOMAP_F_NEW) ||
|
|
offset >= i_size_read(inode)) {
|
|
/*
|
|
* This can happen if truncating the block device races
|
|
* with the check in the caller as i_size updates on
|
|
* block devices aren't synchronized by i_rwsem for
|
|
* block devices.
|
|
*/
|
|
if (S_ISBLK(inode->i_mode))
|
|
return -EIO;
|
|
set_buffer_new(bh);
|
|
}
|
|
bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
|
|
inode->i_blkbits;
|
|
set_buffer_mapped(bh);
|
|
return 0;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
return -EIO;
|
|
}
|
|
}
|
|
|
|
int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len,
|
|
get_block_t *get_block, const struct iomap *iomap)
|
|
{
|
|
unsigned from = pos & (PAGE_SIZE - 1);
|
|
unsigned to = from + len;
|
|
struct inode *inode = folio->mapping->host;
|
|
unsigned block_start, block_end;
|
|
sector_t block;
|
|
int err = 0;
|
|
unsigned blocksize, bbits;
|
|
struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
BUG_ON(from > PAGE_SIZE);
|
|
BUG_ON(to > PAGE_SIZE);
|
|
BUG_ON(from > to);
|
|
|
|
head = folio_create_buffers(folio, inode, 0);
|
|
blocksize = head->b_size;
|
|
bbits = block_size_bits(blocksize);
|
|
|
|
block = (sector_t)folio->index << (PAGE_SHIFT - bbits);
|
|
|
|
for(bh = head, block_start = 0; bh != head || !block_start;
|
|
block++, block_start=block_end, bh = bh->b_this_page) {
|
|
block_end = block_start + blocksize;
|
|
if (block_end <= from || block_start >= to) {
|
|
if (folio_test_uptodate(folio)) {
|
|
if (!buffer_uptodate(bh))
|
|
set_buffer_uptodate(bh);
|
|
}
|
|
continue;
|
|
}
|
|
if (buffer_new(bh))
|
|
clear_buffer_new(bh);
|
|
if (!buffer_mapped(bh)) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
if (get_block)
|
|
err = get_block(inode, block, bh, 1);
|
|
else
|
|
err = iomap_to_bh(inode, block, bh, iomap);
|
|
if (err)
|
|
break;
|
|
|
|
if (buffer_new(bh)) {
|
|
clean_bdev_bh_alias(bh);
|
|
if (folio_test_uptodate(folio)) {
|
|
clear_buffer_new(bh);
|
|
set_buffer_uptodate(bh);
|
|
mark_buffer_dirty(bh);
|
|
continue;
|
|
}
|
|
if (block_end > to || block_start < from)
|
|
folio_zero_segments(folio,
|
|
to, block_end,
|
|
block_start, from);
|
|
continue;
|
|
}
|
|
}
|
|
if (folio_test_uptodate(folio)) {
|
|
if (!buffer_uptodate(bh))
|
|
set_buffer_uptodate(bh);
|
|
continue;
|
|
}
|
|
if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
|
|
!buffer_unwritten(bh) &&
|
|
(block_start < from || block_end > to)) {
|
|
bh_read_nowait(bh, 0);
|
|
*wait_bh++=bh;
|
|
}
|
|
}
|
|
/*
|
|
* If we issued read requests - let them complete.
|
|
*/
|
|
while(wait_bh > wait) {
|
|
wait_on_buffer(*--wait_bh);
|
|
if (!buffer_uptodate(*wait_bh))
|
|
err = -EIO;
|
|
}
|
|
if (unlikely(err))
|
|
folio_zero_new_buffers(folio, from, to);
|
|
return err;
|
|
}
|
|
|
|
int __block_write_begin(struct page *page, loff_t pos, unsigned len,
|
|
get_block_t *get_block)
|
|
{
|
|
return __block_write_begin_int(page_folio(page), pos, len, get_block,
|
|
NULL);
|
|
}
|
|
EXPORT_SYMBOL(__block_write_begin);
|
|
|
|
static void __block_commit_write(struct folio *folio, size_t from, size_t to)
|
|
{
|
|
size_t block_start, block_end;
|
|
bool partial = false;
|
|
unsigned blocksize;
|
|
struct buffer_head *bh, *head;
|
|
|
|
bh = head = folio_buffers(folio);
|
|
blocksize = bh->b_size;
|
|
|
|
block_start = 0;
|
|
do {
|
|
block_end = block_start + blocksize;
|
|
if (block_end <= from || block_start >= to) {
|
|
if (!buffer_uptodate(bh))
|
|
partial = true;
|
|
} else {
|
|
set_buffer_uptodate(bh);
|
|
mark_buffer_dirty(bh);
|
|
}
|
|
if (buffer_new(bh))
|
|
clear_buffer_new(bh);
|
|
|
|
block_start = block_end;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* If this is a partial write which happened to make all buffers
|
|
* uptodate then we can optimize away a bogus read_folio() for
|
|
* the next read(). Here we 'discover' whether the folio went
|
|
* uptodate as a result of this (potentially partial) write.
|
|
*/
|
|
if (!partial)
|
|
folio_mark_uptodate(folio);
|
|
}
|
|
|
|
/*
|
|
* block_write_begin takes care of the basic task of block allocation and
|
|
* bringing partial write blocks uptodate first.
|
|
*
|
|
* The filesystem needs to handle block truncation upon failure.
|
|
*/
|
|
int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
|
|
struct page **pagep, get_block_t *get_block)
|
|
{
|
|
pgoff_t index = pos >> PAGE_SHIFT;
|
|
struct page *page;
|
|
int status;
|
|
|
|
page = grab_cache_page_write_begin(mapping, index);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
status = __block_write_begin(page, pos, len, get_block);
|
|
if (unlikely(status)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
page = NULL;
|
|
}
|
|
|
|
*pagep = page;
|
|
return status;
|
|
}
|
|
EXPORT_SYMBOL(block_write_begin);
|
|
|
|
int block_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
struct folio *folio = page_folio(page);
|
|
size_t start = pos - folio_pos(folio);
|
|
|
|
if (unlikely(copied < len)) {
|
|
/*
|
|
* The buffers that were written will now be uptodate, so
|
|
* we don't have to worry about a read_folio reading them
|
|
* and overwriting a partial write. However if we have
|
|
* encountered a short write and only partially written
|
|
* into a buffer, it will not be marked uptodate, so a
|
|
* read_folio might come in and destroy our partial write.
|
|
*
|
|
* Do the simplest thing, and just treat any short write to a
|
|
* non uptodate folio as a zero-length write, and force the
|
|
* caller to redo the whole thing.
|
|
*/
|
|
if (!folio_test_uptodate(folio))
|
|
copied = 0;
|
|
|
|
folio_zero_new_buffers(folio, start+copied, start+len);
|
|
}
|
|
flush_dcache_folio(folio);
|
|
|
|
/* This could be a short (even 0-length) commit */
|
|
__block_commit_write(folio, start, start + copied);
|
|
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(block_write_end);
|
|
|
|
int generic_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
loff_t old_size = inode->i_size;
|
|
bool i_size_changed = false;
|
|
|
|
copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
|
|
|
|
/*
|
|
* No need to use i_size_read() here, the i_size cannot change under us
|
|
* because we hold i_rwsem.
|
|
*
|
|
* But it's important to update i_size while still holding page lock:
|
|
* page writeout could otherwise come in and zero beyond i_size.
|
|
*/
|
|
if (pos + copied > inode->i_size) {
|
|
i_size_write(inode, pos + copied);
|
|
i_size_changed = true;
|
|
}
|
|
|
|
unlock_page(page);
|
|
put_page(page);
|
|
|
|
if (old_size < pos)
|
|
pagecache_isize_extended(inode, old_size, pos);
|
|
/*
|
|
* Don't mark the inode dirty under page lock. First, it unnecessarily
|
|
* makes the holding time of page lock longer. Second, it forces lock
|
|
* ordering of page lock and transaction start for journaling
|
|
* filesystems.
|
|
*/
|
|
if (i_size_changed)
|
|
mark_inode_dirty(inode);
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(generic_write_end);
|
|
|
|
/*
|
|
* block_is_partially_uptodate checks whether buffers within a folio are
|
|
* uptodate or not.
|
|
*
|
|
* Returns true if all buffers which correspond to the specified part
|
|
* of the folio are uptodate.
|
|
*/
|
|
bool block_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
|
|
{
|
|
unsigned block_start, block_end, blocksize;
|
|
unsigned to;
|
|
struct buffer_head *bh, *head;
|
|
bool ret = true;
|
|
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
return false;
|
|
blocksize = head->b_size;
|
|
to = min_t(unsigned, folio_size(folio) - from, count);
|
|
to = from + to;
|
|
if (from < blocksize && to > folio_size(folio) - blocksize)
|
|
return false;
|
|
|
|
bh = head;
|
|
block_start = 0;
|
|
do {
|
|
block_end = block_start + blocksize;
|
|
if (block_end > from && block_start < to) {
|
|
if (!buffer_uptodate(bh)) {
|
|
ret = false;
|
|
break;
|
|
}
|
|
if (block_end >= to)
|
|
break;
|
|
}
|
|
block_start = block_end;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(block_is_partially_uptodate);
|
|
|
|
/*
|
|
* Generic "read_folio" function for block devices that have the normal
|
|
* get_block functionality. This is most of the block device filesystems.
|
|
* Reads the folio asynchronously --- the unlock_buffer() and
|
|
* set/clear_buffer_uptodate() functions propagate buffer state into the
|
|
* folio once IO has completed.
|
|
*/
|
|
int block_read_full_folio(struct folio *folio, get_block_t *get_block)
|
|
{
|
|
struct inode *inode = folio->mapping->host;
|
|
sector_t iblock, lblock;
|
|
struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
|
|
unsigned int blocksize, bbits;
|
|
int nr, i;
|
|
int fully_mapped = 1;
|
|
bool page_error = false;
|
|
loff_t limit = i_size_read(inode);
|
|
|
|
/* This is needed for ext4. */
|
|
if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
|
|
limit = inode->i_sb->s_maxbytes;
|
|
|
|
VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
|
|
|
|
head = folio_create_buffers(folio, inode, 0);
|
|
blocksize = head->b_size;
|
|
bbits = block_size_bits(blocksize);
|
|
|
|
iblock = (sector_t)folio->index << (PAGE_SHIFT - bbits);
|
|
lblock = (limit+blocksize-1) >> bbits;
|
|
bh = head;
|
|
nr = 0;
|
|
i = 0;
|
|
|
|
do {
|
|
if (buffer_uptodate(bh))
|
|
continue;
|
|
|
|
if (!buffer_mapped(bh)) {
|
|
int err = 0;
|
|
|
|
fully_mapped = 0;
|
|
if (iblock < lblock) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
err = get_block(inode, iblock, bh, 0);
|
|
if (err) {
|
|
folio_set_error(folio);
|
|
page_error = true;
|
|
}
|
|
}
|
|
if (!buffer_mapped(bh)) {
|
|
folio_zero_range(folio, i * blocksize,
|
|
blocksize);
|
|
if (!err)
|
|
set_buffer_uptodate(bh);
|
|
continue;
|
|
}
|
|
/*
|
|
* get_block() might have updated the buffer
|
|
* synchronously
|
|
*/
|
|
if (buffer_uptodate(bh))
|
|
continue;
|
|
}
|
|
arr[nr++] = bh;
|
|
} while (i++, iblock++, (bh = bh->b_this_page) != head);
|
|
|
|
if (fully_mapped)
|
|
folio_set_mappedtodisk(folio);
|
|
|
|
if (!nr) {
|
|
/*
|
|
* All buffers are uptodate - we can set the folio uptodate
|
|
* as well. But not if get_block() returned an error.
|
|
*/
|
|
if (!page_error)
|
|
folio_mark_uptodate(folio);
|
|
folio_unlock(folio);
|
|
return 0;
|
|
}
|
|
|
|
/* Stage two: lock the buffers */
|
|
for (i = 0; i < nr; i++) {
|
|
bh = arr[i];
|
|
lock_buffer(bh);
|
|
mark_buffer_async_read(bh);
|
|
}
|
|
|
|
/*
|
|
* Stage 3: start the IO. Check for uptodateness
|
|
* inside the buffer lock in case another process reading
|
|
* the underlying blockdev brought it uptodate (the sct fix).
|
|
*/
|
|
for (i = 0; i < nr; i++) {
|
|
bh = arr[i];
|
|
if (buffer_uptodate(bh))
|
|
end_buffer_async_read(bh, 1);
|
|
else
|
|
submit_bh(REQ_OP_READ, bh);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(block_read_full_folio);
|
|
|
|
/* utility function for filesystems that need to do work on expanding
|
|
* truncates. Uses filesystem pagecache writes to allow the filesystem to
|
|
* deal with the hole.
|
|
*/
|
|
int generic_cont_expand_simple(struct inode *inode, loff_t size)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
struct page *page;
|
|
void *fsdata = NULL;
|
|
int err;
|
|
|
|
err = inode_newsize_ok(inode, size);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = aops->write_begin(NULL, mapping, size, 0, &page, &fsdata);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = aops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
|
|
BUG_ON(err > 0);
|
|
|
|
out:
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(generic_cont_expand_simple);
|
|
|
|
static int cont_expand_zero(struct file *file, struct address_space *mapping,
|
|
loff_t pos, loff_t *bytes)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
unsigned int blocksize = i_blocksize(inode);
|
|
struct page *page;
|
|
void *fsdata = NULL;
|
|
pgoff_t index, curidx;
|
|
loff_t curpos;
|
|
unsigned zerofrom, offset, len;
|
|
int err = 0;
|
|
|
|
index = pos >> PAGE_SHIFT;
|
|
offset = pos & ~PAGE_MASK;
|
|
|
|
while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) {
|
|
zerofrom = curpos & ~PAGE_MASK;
|
|
if (zerofrom & (blocksize-1)) {
|
|
*bytes |= (blocksize-1);
|
|
(*bytes)++;
|
|
}
|
|
len = PAGE_SIZE - zerofrom;
|
|
|
|
err = aops->write_begin(file, mapping, curpos, len,
|
|
&page, &fsdata);
|
|
if (err)
|
|
goto out;
|
|
zero_user(page, zerofrom, len);
|
|
err = aops->write_end(file, mapping, curpos, len, len,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto out;
|
|
BUG_ON(err != len);
|
|
err = 0;
|
|
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
err = -EINTR;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* page covers the boundary, find the boundary offset */
|
|
if (index == curidx) {
|
|
zerofrom = curpos & ~PAGE_MASK;
|
|
/* if we will expand the thing last block will be filled */
|
|
if (offset <= zerofrom) {
|
|
goto out;
|
|
}
|
|
if (zerofrom & (blocksize-1)) {
|
|
*bytes |= (blocksize-1);
|
|
(*bytes)++;
|
|
}
|
|
len = offset - zerofrom;
|
|
|
|
err = aops->write_begin(file, mapping, curpos, len,
|
|
&page, &fsdata);
|
|
if (err)
|
|
goto out;
|
|
zero_user(page, zerofrom, len);
|
|
err = aops->write_end(file, mapping, curpos, len, len,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto out;
|
|
BUG_ON(err != len);
|
|
err = 0;
|
|
}
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* For moronic filesystems that do not allow holes in file.
|
|
* We may have to extend the file.
|
|
*/
|
|
int cont_write_begin(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len,
|
|
struct page **pagep, void **fsdata,
|
|
get_block_t *get_block, loff_t *bytes)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
unsigned int blocksize = i_blocksize(inode);
|
|
unsigned int zerofrom;
|
|
int err;
|
|
|
|
err = cont_expand_zero(file, mapping, pos, bytes);
|
|
if (err)
|
|
return err;
|
|
|
|
zerofrom = *bytes & ~PAGE_MASK;
|
|
if (pos+len > *bytes && zerofrom & (blocksize-1)) {
|
|
*bytes |= (blocksize-1);
|
|
(*bytes)++;
|
|
}
|
|
|
|
return block_write_begin(mapping, pos, len, pagep, get_block);
|
|
}
|
|
EXPORT_SYMBOL(cont_write_begin);
|
|
|
|
void block_commit_write(struct page *page, unsigned from, unsigned to)
|
|
{
|
|
struct folio *folio = page_folio(page);
|
|
__block_commit_write(folio, from, to);
|
|
}
|
|
EXPORT_SYMBOL(block_commit_write);
|
|
|
|
/*
|
|
* block_page_mkwrite() is not allowed to change the file size as it gets
|
|
* called from a page fault handler when a page is first dirtied. Hence we must
|
|
* be careful to check for EOF conditions here. We set the page up correctly
|
|
* for a written page which means we get ENOSPC checking when writing into
|
|
* holes and correct delalloc and unwritten extent mapping on filesystems that
|
|
* support these features.
|
|
*
|
|
* We are not allowed to take the i_mutex here so we have to play games to
|
|
* protect against truncate races as the page could now be beyond EOF. Because
|
|
* truncate writes the inode size before removing pages, once we have the
|
|
* page lock we can determine safely if the page is beyond EOF. If it is not
|
|
* beyond EOF, then the page is guaranteed safe against truncation until we
|
|
* unlock the page.
|
|
*
|
|
* Direct callers of this function should protect against filesystem freezing
|
|
* using sb_start_pagefault() - sb_end_pagefault() functions.
|
|
*/
|
|
int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
|
|
get_block_t get_block)
|
|
{
|
|
struct folio *folio = page_folio(vmf->page);
|
|
struct inode *inode = file_inode(vma->vm_file);
|
|
unsigned long end;
|
|
loff_t size;
|
|
int ret;
|
|
|
|
folio_lock(folio);
|
|
size = i_size_read(inode);
|
|
if ((folio->mapping != inode->i_mapping) ||
|
|
(folio_pos(folio) >= size)) {
|
|
/* We overload EFAULT to mean page got truncated */
|
|
ret = -EFAULT;
|
|
goto out_unlock;
|
|
}
|
|
|
|
end = folio_size(folio);
|
|
/* folio is wholly or partially inside EOF */
|
|
if (folio_pos(folio) + end > size)
|
|
end = size - folio_pos(folio);
|
|
|
|
ret = __block_write_begin_int(folio, 0, end, get_block, NULL);
|
|
if (unlikely(ret))
|
|
goto out_unlock;
|
|
|
|
__block_commit_write(folio, 0, end);
|
|
|
|
folio_mark_dirty(folio);
|
|
folio_wait_stable(folio);
|
|
return 0;
|
|
out_unlock:
|
|
folio_unlock(folio);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(block_page_mkwrite);
|
|
|
|
int block_truncate_page(struct address_space *mapping,
|
|
loff_t from, get_block_t *get_block)
|
|
{
|
|
pgoff_t index = from >> PAGE_SHIFT;
|
|
unsigned blocksize;
|
|
sector_t iblock;
|
|
size_t offset, length, pos;
|
|
struct inode *inode = mapping->host;
|
|
struct folio *folio;
|
|
struct buffer_head *bh;
|
|
int err = 0;
|
|
|
|
blocksize = i_blocksize(inode);
|
|
length = from & (blocksize - 1);
|
|
|
|
/* Block boundary? Nothing to do */
|
|
if (!length)
|
|
return 0;
|
|
|
|
length = blocksize - length;
|
|
iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits);
|
|
|
|
folio = filemap_grab_folio(mapping, index);
|
|
if (IS_ERR(folio))
|
|
return PTR_ERR(folio);
|
|
|
|
bh = folio_buffers(folio);
|
|
if (!bh) {
|
|
folio_create_empty_buffers(folio, blocksize, 0);
|
|
bh = folio_buffers(folio);
|
|
}
|
|
|
|
/* Find the buffer that contains "offset" */
|
|
offset = offset_in_folio(folio, from);
|
|
pos = blocksize;
|
|
while (offset >= pos) {
|
|
bh = bh->b_this_page;
|
|
iblock++;
|
|
pos += blocksize;
|
|
}
|
|
|
|
if (!buffer_mapped(bh)) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
err = get_block(inode, iblock, bh, 0);
|
|
if (err)
|
|
goto unlock;
|
|
/* unmapped? It's a hole - nothing to do */
|
|
if (!buffer_mapped(bh))
|
|
goto unlock;
|
|
}
|
|
|
|
/* Ok, it's mapped. Make sure it's up-to-date */
|
|
if (folio_test_uptodate(folio))
|
|
set_buffer_uptodate(bh);
|
|
|
|
if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
|
|
err = bh_read(bh, 0);
|
|
/* Uhhuh. Read error. Complain and punt. */
|
|
if (err < 0)
|
|
goto unlock;
|
|
}
|
|
|
|
folio_zero_range(folio, offset, length);
|
|
mark_buffer_dirty(bh);
|
|
|
|
unlock:
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(block_truncate_page);
|
|
|
|
/*
|
|
* The generic ->writepage function for buffer-backed address_spaces
|
|
*/
|
|
int block_write_full_page(struct page *page, get_block_t *get_block,
|
|
struct writeback_control *wbc)
|
|
{
|
|
struct folio *folio = page_folio(page);
|
|
struct inode * const inode = folio->mapping->host;
|
|
loff_t i_size = i_size_read(inode);
|
|
|
|
/* Is the folio fully inside i_size? */
|
|
if (folio_pos(folio) + folio_size(folio) <= i_size)
|
|
return __block_write_full_folio(inode, folio, get_block, wbc,
|
|
end_buffer_async_write);
|
|
|
|
/* Is the folio fully outside i_size? (truncate in progress) */
|
|
if (folio_pos(folio) >= i_size) {
|
|
folio_unlock(folio);
|
|
return 0; /* don't care */
|
|
}
|
|
|
|
/*
|
|
* The folio straddles i_size. It must be zeroed out on each and every
|
|
* writepage invocation because it may be mmapped. "A file is mapped
|
|
* in multiples of the page size. For a file that is not a multiple of
|
|
* the page size, the remaining memory is zeroed when mapped, and
|
|
* writes to that region are not written out to the file."
|
|
*/
|
|
folio_zero_segment(folio, offset_in_folio(folio, i_size),
|
|
folio_size(folio));
|
|
return __block_write_full_folio(inode, folio, get_block, wbc,
|
|
end_buffer_async_write);
|
|
}
|
|
EXPORT_SYMBOL(block_write_full_page);
|
|
|
|
sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
|
|
get_block_t *get_block)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
struct buffer_head tmp = {
|
|
.b_size = i_blocksize(inode),
|
|
};
|
|
|
|
get_block(inode, block, &tmp, 0);
|
|
return tmp.b_blocknr;
|
|
}
|
|
EXPORT_SYMBOL(generic_block_bmap);
|
|
|
|
static void end_bio_bh_io_sync(struct bio *bio)
|
|
{
|
|
struct buffer_head *bh = bio->bi_private;
|
|
|
|
if (unlikely(bio_flagged(bio, BIO_QUIET)))
|
|
set_bit(BH_Quiet, &bh->b_state);
|
|
|
|
bh->b_end_io(bh, !bio->bi_status);
|
|
bio_put(bio);
|
|
}
|
|
|
|
static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
|
|
struct writeback_control *wbc)
|
|
{
|
|
const enum req_op op = opf & REQ_OP_MASK;
|
|
struct bio *bio;
|
|
|
|
BUG_ON(!buffer_locked(bh));
|
|
BUG_ON(!buffer_mapped(bh));
|
|
BUG_ON(!bh->b_end_io);
|
|
BUG_ON(buffer_delay(bh));
|
|
BUG_ON(buffer_unwritten(bh));
|
|
|
|
/*
|
|
* Only clear out a write error when rewriting
|
|
*/
|
|
if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE))
|
|
clear_buffer_write_io_error(bh);
|
|
|
|
if (buffer_meta(bh))
|
|
opf |= REQ_META;
|
|
if (buffer_prio(bh))
|
|
opf |= REQ_PRIO;
|
|
|
|
bio = bio_alloc(bh->b_bdev, 1, opf, GFP_NOIO);
|
|
|
|
fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
|
|
|
|
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
|
|
|
|
__bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
|
|
|
|
bio->bi_end_io = end_bio_bh_io_sync;
|
|
bio->bi_private = bh;
|
|
|
|
/* Take care of bh's that straddle the end of the device */
|
|
guard_bio_eod(bio);
|
|
|
|
if (wbc) {
|
|
wbc_init_bio(wbc, bio);
|
|
wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size);
|
|
}
|
|
|
|
submit_bio(bio);
|
|
}
|
|
|
|
void submit_bh(blk_opf_t opf, struct buffer_head *bh)
|
|
{
|
|
submit_bh_wbc(opf, bh, NULL);
|
|
}
|
|
EXPORT_SYMBOL(submit_bh);
|
|
|
|
void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags)
|
|
{
|
|
lock_buffer(bh);
|
|
if (!test_clear_buffer_dirty(bh)) {
|
|
unlock_buffer(bh);
|
|
return;
|
|
}
|
|
bh->b_end_io = end_buffer_write_sync;
|
|
get_bh(bh);
|
|
submit_bh(REQ_OP_WRITE | op_flags, bh);
|
|
}
|
|
EXPORT_SYMBOL(write_dirty_buffer);
|
|
|
|
/*
|
|
* For a data-integrity writeout, we need to wait upon any in-progress I/O
|
|
* and then start new I/O and then wait upon it. The caller must have a ref on
|
|
* the buffer_head.
|
|
*/
|
|
int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags)
|
|
{
|
|
WARN_ON(atomic_read(&bh->b_count) < 1);
|
|
lock_buffer(bh);
|
|
if (test_clear_buffer_dirty(bh)) {
|
|
/*
|
|
* The bh should be mapped, but it might not be if the
|
|
* device was hot-removed. Not much we can do but fail the I/O.
|
|
*/
|
|
if (!buffer_mapped(bh)) {
|
|
unlock_buffer(bh);
|
|
return -EIO;
|
|
}
|
|
|
|
get_bh(bh);
|
|
bh->b_end_io = end_buffer_write_sync;
|
|
submit_bh(REQ_OP_WRITE | op_flags, bh);
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
return -EIO;
|
|
} else {
|
|
unlock_buffer(bh);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(__sync_dirty_buffer);
|
|
|
|
int sync_dirty_buffer(struct buffer_head *bh)
|
|
{
|
|
return __sync_dirty_buffer(bh, REQ_SYNC);
|
|
}
|
|
EXPORT_SYMBOL(sync_dirty_buffer);
|
|
|
|
/*
|
|
* try_to_free_buffers() checks if all the buffers on this particular folio
|
|
* are unused, and releases them if so.
|
|
*
|
|
* Exclusion against try_to_free_buffers may be obtained by either
|
|
* locking the folio or by holding its mapping's private_lock.
|
|
*
|
|
* If the folio is dirty but all the buffers are clean then we need to
|
|
* be sure to mark the folio clean as well. This is because the folio
|
|
* may be against a block device, and a later reattachment of buffers
|
|
* to a dirty folio will set *all* buffers dirty. Which would corrupt
|
|
* filesystem data on the same device.
|
|
*
|
|
* The same applies to regular filesystem folios: if all the buffers are
|
|
* clean then we set the folio clean and proceed. To do that, we require
|
|
* total exclusion from block_dirty_folio(). That is obtained with
|
|
* private_lock.
|
|
*
|
|
* try_to_free_buffers() is non-blocking.
|
|
*/
|
|
static inline int buffer_busy(struct buffer_head *bh)
|
|
{
|
|
return atomic_read(&bh->b_count) |
|
|
(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
|
|
}
|
|
|
|
static bool
|
|
drop_buffers(struct folio *folio, struct buffer_head **buffers_to_free)
|
|
{
|
|
struct buffer_head *head = folio_buffers(folio);
|
|
struct buffer_head *bh;
|
|
|
|
bh = head;
|
|
do {
|
|
if (buffer_busy(bh))
|
|
goto failed;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
|
|
if (bh->b_assoc_map)
|
|
__remove_assoc_queue(bh);
|
|
bh = next;
|
|
} while (bh != head);
|
|
*buffers_to_free = head;
|
|
folio_detach_private(folio);
|
|
return true;
|
|
failed:
|
|
return false;
|
|
}
|
|
|
|
bool try_to_free_buffers(struct folio *folio)
|
|
{
|
|
struct address_space * const mapping = folio->mapping;
|
|
struct buffer_head *buffers_to_free = NULL;
|
|
bool ret = 0;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
if (folio_test_writeback(folio))
|
|
return false;
|
|
|
|
if (mapping == NULL) { /* can this still happen? */
|
|
ret = drop_buffers(folio, &buffers_to_free);
|
|
goto out;
|
|
}
|
|
|
|
spin_lock(&mapping->private_lock);
|
|
ret = drop_buffers(folio, &buffers_to_free);
|
|
|
|
/*
|
|
* If the filesystem writes its buffers by hand (eg ext3)
|
|
* then we can have clean buffers against a dirty folio. We
|
|
* clean the folio here; otherwise the VM will never notice
|
|
* that the filesystem did any IO at all.
|
|
*
|
|
* Also, during truncate, discard_buffer will have marked all
|
|
* the folio's buffers clean. We discover that here and clean
|
|
* the folio also.
|
|
*
|
|
* private_lock must be held over this entire operation in order
|
|
* to synchronise against block_dirty_folio and prevent the
|
|
* dirty bit from being lost.
|
|
*/
|
|
if (ret)
|
|
folio_cancel_dirty(folio);
|
|
spin_unlock(&mapping->private_lock);
|
|
out:
|
|
if (buffers_to_free) {
|
|
struct buffer_head *bh = buffers_to_free;
|
|
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
free_buffer_head(bh);
|
|
bh = next;
|
|
} while (bh != buffers_to_free);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(try_to_free_buffers);
|
|
|
|
/*
|
|
* Buffer-head allocation
|
|
*/
|
|
static struct kmem_cache *bh_cachep __read_mostly;
|
|
|
|
/*
|
|
* Once the number of bh's in the machine exceeds this level, we start
|
|
* stripping them in writeback.
|
|
*/
|
|
static unsigned long max_buffer_heads;
|
|
|
|
int buffer_heads_over_limit;
|
|
|
|
struct bh_accounting {
|
|
int nr; /* Number of live bh's */
|
|
int ratelimit; /* Limit cacheline bouncing */
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
|
|
|
|
static void recalc_bh_state(void)
|
|
{
|
|
int i;
|
|
int tot = 0;
|
|
|
|
if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
|
|
return;
|
|
__this_cpu_write(bh_accounting.ratelimit, 0);
|
|
for_each_online_cpu(i)
|
|
tot += per_cpu(bh_accounting, i).nr;
|
|
buffer_heads_over_limit = (tot > max_buffer_heads);
|
|
}
|
|
|
|
struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
|
|
{
|
|
struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
|
|
if (ret) {
|
|
INIT_LIST_HEAD(&ret->b_assoc_buffers);
|
|
spin_lock_init(&ret->b_uptodate_lock);
|
|
preempt_disable();
|
|
__this_cpu_inc(bh_accounting.nr);
|
|
recalc_bh_state();
|
|
preempt_enable();
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(alloc_buffer_head);
|
|
|
|
void free_buffer_head(struct buffer_head *bh)
|
|
{
|
|
BUG_ON(!list_empty(&bh->b_assoc_buffers));
|
|
kmem_cache_free(bh_cachep, bh);
|
|
preempt_disable();
|
|
__this_cpu_dec(bh_accounting.nr);
|
|
recalc_bh_state();
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(free_buffer_head);
|
|
|
|
static int buffer_exit_cpu_dead(unsigned int cpu)
|
|
{
|
|
int i;
|
|
struct bh_lru *b = &per_cpu(bh_lrus, cpu);
|
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
brelse(b->bhs[i]);
|
|
b->bhs[i] = NULL;
|
|
}
|
|
this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
|
|
per_cpu(bh_accounting, cpu).nr = 0;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* bh_uptodate_or_lock - Test whether the buffer is uptodate
|
|
* @bh: struct buffer_head
|
|
*
|
|
* Return true if the buffer is up-to-date and false,
|
|
* with the buffer locked, if not.
|
|
*/
|
|
int bh_uptodate_or_lock(struct buffer_head *bh)
|
|
{
|
|
if (!buffer_uptodate(bh)) {
|
|
lock_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
return 0;
|
|
unlock_buffer(bh);
|
|
}
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(bh_uptodate_or_lock);
|
|
|
|
/**
|
|
* __bh_read - Submit read for a locked buffer
|
|
* @bh: struct buffer_head
|
|
* @op_flags: appending REQ_OP_* flags besides REQ_OP_READ
|
|
* @wait: wait until reading finish
|
|
*
|
|
* Returns zero on success or don't wait, and -EIO on error.
|
|
*/
|
|
int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait)
|
|
{
|
|
int ret = 0;
|
|
|
|
BUG_ON(!buffer_locked(bh));
|
|
|
|
get_bh(bh);
|
|
bh->b_end_io = end_buffer_read_sync;
|
|
submit_bh(REQ_OP_READ | op_flags, bh);
|
|
if (wait) {
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
ret = -EIO;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__bh_read);
|
|
|
|
/**
|
|
* __bh_read_batch - Submit read for a batch of unlocked buffers
|
|
* @nr: entry number of the buffer batch
|
|
* @bhs: a batch of struct buffer_head
|
|
* @op_flags: appending REQ_OP_* flags besides REQ_OP_READ
|
|
* @force_lock: force to get a lock on the buffer if set, otherwise drops any
|
|
* buffer that cannot lock.
|
|
*
|
|
* Returns zero on success or don't wait, and -EIO on error.
|
|
*/
|
|
void __bh_read_batch(int nr, struct buffer_head *bhs[],
|
|
blk_opf_t op_flags, bool force_lock)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct buffer_head *bh = bhs[i];
|
|
|
|
if (buffer_uptodate(bh))
|
|
continue;
|
|
|
|
if (force_lock)
|
|
lock_buffer(bh);
|
|
else
|
|
if (!trylock_buffer(bh))
|
|
continue;
|
|
|
|
if (buffer_uptodate(bh)) {
|
|
unlock_buffer(bh);
|
|
continue;
|
|
}
|
|
|
|
bh->b_end_io = end_buffer_read_sync;
|
|
get_bh(bh);
|
|
submit_bh(REQ_OP_READ | op_flags, bh);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__bh_read_batch);
|
|
|
|
void __init buffer_init(void)
|
|
{
|
|
unsigned long nrpages;
|
|
int ret;
|
|
|
|
bh_cachep = kmem_cache_create("buffer_head",
|
|
sizeof(struct buffer_head), 0,
|
|
(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
|
|
SLAB_MEM_SPREAD),
|
|
NULL);
|
|
|
|
/*
|
|
* Limit the bh occupancy to 10% of ZONE_NORMAL
|
|
*/
|
|
nrpages = (nr_free_buffer_pages() * 10) / 100;
|
|
max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
|
|
ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead",
|
|
NULL, buffer_exit_cpu_dead);
|
|
WARN_ON(ret < 0);
|
|
}
|