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![Linus Torvalds](/assets/img/avatar_default.png)
Pull VFS updates from Al Viro, Misc cleanups all over the place, mainly wrt /proc interfaces (switch create_proc_entry to proc_create(), get rid of the deprecated create_proc_read_entry() in favor of using proc_create_data() and seq_file etc). 7kloc removed. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits) don't bother with deferred freeing of fdtables proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h proc: Make the PROC_I() and PDE() macros internal to procfs proc: Supply a function to remove a proc entry by PDE take cgroup_open() and cpuset_open() to fs/proc/base.c ppc: Clean up scanlog ppc: Clean up rtas_flash driver somewhat hostap: proc: Use remove_proc_subtree() drm: proc: Use remove_proc_subtree() drm: proc: Use minor->index to label things, not PDE->name drm: Constify drm_proc_list[] zoran: Don't print proc_dir_entry data in debug reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show() proc: Supply an accessor for getting the data from a PDE's parent airo: Use remove_proc_subtree() rtl8192u: Don't need to save device proc dir PDE rtl8187se: Use a dir under /proc/net/r8180/ proc: Add proc_mkdir_data() proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h} proc: Move PDE_NET() to fs/proc/proc_net.c ...
2594 lines
68 KiB
C
2594 lines
68 KiB
C
/*
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* linux/mm/filemap.c
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*
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* Copyright (C) 1994-1999 Linus Torvalds
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*/
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/*
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* This file handles the generic file mmap semantics used by
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* most "normal" filesystems (but you don't /have/ to use this:
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* the NFS filesystem used to do this differently, for example)
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*/
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#include <linux/export.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/aio.h>
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#include <linux/capability.h>
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#include <linux/kernel_stat.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/hash.h>
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#include <linux/writeback.h>
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#include <linux/backing-dev.h>
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#include <linux/pagevec.h>
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#include <linux/blkdev.h>
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#include <linux/security.h>
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#include <linux/cpuset.h>
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#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
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#include <linux/memcontrol.h>
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#include <linux/cleancache.h>
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#include "internal.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/filemap.h>
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/*
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* FIXME: remove all knowledge of the buffer layer from the core VM
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*/
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#include <linux/buffer_head.h> /* for try_to_free_buffers */
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#include <asm/mman.h>
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/*
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* Shared mappings implemented 30.11.1994. It's not fully working yet,
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* though.
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*
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* Shared mappings now work. 15.8.1995 Bruno.
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*
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* finished 'unifying' the page and buffer cache and SMP-threaded the
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* page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
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*
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* SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
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*/
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/*
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* Lock ordering:
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*
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* ->i_mmap_mutex (truncate_pagecache)
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* ->private_lock (__free_pte->__set_page_dirty_buffers)
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* ->swap_lock (exclusive_swap_page, others)
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* ->mapping->tree_lock
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*
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* ->i_mutex
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* ->i_mmap_mutex (truncate->unmap_mapping_range)
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*
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* ->mmap_sem
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* ->i_mmap_mutex
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* ->page_table_lock or pte_lock (various, mainly in memory.c)
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* ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
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*
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* ->mmap_sem
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* ->lock_page (access_process_vm)
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*
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* ->i_mutex (generic_file_buffered_write)
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* ->mmap_sem (fault_in_pages_readable->do_page_fault)
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*
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* bdi->wb.list_lock
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* sb_lock (fs/fs-writeback.c)
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* ->mapping->tree_lock (__sync_single_inode)
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*
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* ->i_mmap_mutex
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* ->anon_vma.lock (vma_adjust)
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*
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* ->anon_vma.lock
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* ->page_table_lock or pte_lock (anon_vma_prepare and various)
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*
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* ->page_table_lock or pte_lock
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* ->swap_lock (try_to_unmap_one)
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* ->private_lock (try_to_unmap_one)
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* ->tree_lock (try_to_unmap_one)
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* ->zone.lru_lock (follow_page->mark_page_accessed)
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* ->zone.lru_lock (check_pte_range->isolate_lru_page)
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* ->private_lock (page_remove_rmap->set_page_dirty)
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* ->tree_lock (page_remove_rmap->set_page_dirty)
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* bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
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* ->inode->i_lock (page_remove_rmap->set_page_dirty)
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* bdi.wb->list_lock (zap_pte_range->set_page_dirty)
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* ->inode->i_lock (zap_pte_range->set_page_dirty)
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* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
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*
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* ->i_mmap_mutex
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* ->tasklist_lock (memory_failure, collect_procs_ao)
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*/
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/*
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* Delete a page from the page cache and free it. Caller has to make
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* sure the page is locked and that nobody else uses it - or that usage
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* is safe. The caller must hold the mapping's tree_lock.
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*/
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void __delete_from_page_cache(struct page *page)
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{
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struct address_space *mapping = page->mapping;
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trace_mm_filemap_delete_from_page_cache(page);
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/*
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* if we're uptodate, flush out into the cleancache, otherwise
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* invalidate any existing cleancache entries. We can't leave
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* stale data around in the cleancache once our page is gone
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*/
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if (PageUptodate(page) && PageMappedToDisk(page))
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cleancache_put_page(page);
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else
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cleancache_invalidate_page(mapping, page);
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radix_tree_delete(&mapping->page_tree, page->index);
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page->mapping = NULL;
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/* Leave page->index set: truncation lookup relies upon it */
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mapping->nrpages--;
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__dec_zone_page_state(page, NR_FILE_PAGES);
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if (PageSwapBacked(page))
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__dec_zone_page_state(page, NR_SHMEM);
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BUG_ON(page_mapped(page));
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/*
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* Some filesystems seem to re-dirty the page even after
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* the VM has canceled the dirty bit (eg ext3 journaling).
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*
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* Fix it up by doing a final dirty accounting check after
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* having removed the page entirely.
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*/
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if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
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dec_zone_page_state(page, NR_FILE_DIRTY);
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dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
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}
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}
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/**
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* delete_from_page_cache - delete page from page cache
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* @page: the page which the kernel is trying to remove from page cache
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*
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* This must be called only on pages that have been verified to be in the page
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* cache and locked. It will never put the page into the free list, the caller
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* has a reference on the page.
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*/
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void delete_from_page_cache(struct page *page)
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{
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struct address_space *mapping = page->mapping;
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void (*freepage)(struct page *);
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BUG_ON(!PageLocked(page));
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freepage = mapping->a_ops->freepage;
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spin_lock_irq(&mapping->tree_lock);
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__delete_from_page_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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if (freepage)
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freepage(page);
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page_cache_release(page);
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}
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EXPORT_SYMBOL(delete_from_page_cache);
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static int sleep_on_page(void *word)
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{
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io_schedule();
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return 0;
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}
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static int sleep_on_page_killable(void *word)
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{
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sleep_on_page(word);
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return fatal_signal_pending(current) ? -EINTR : 0;
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}
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static int filemap_check_errors(struct address_space *mapping)
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{
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int ret = 0;
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/* Check for outstanding write errors */
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if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
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ret = -ENOSPC;
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if (test_and_clear_bit(AS_EIO, &mapping->flags))
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ret = -EIO;
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return ret;
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}
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/**
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* __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
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* @mapping: address space structure to write
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* @start: offset in bytes where the range starts
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* @end: offset in bytes where the range ends (inclusive)
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* @sync_mode: enable synchronous operation
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*
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* Start writeback against all of a mapping's dirty pages that lie
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* within the byte offsets <start, end> inclusive.
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*
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* If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
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* opposed to a regular memory cleansing writeback. The difference between
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* these two operations is that if a dirty page/buffer is encountered, it must
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* be waited upon, and not just skipped over.
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*/
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int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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loff_t end, int sync_mode)
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{
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int ret;
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struct writeback_control wbc = {
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.sync_mode = sync_mode,
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.nr_to_write = LONG_MAX,
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.range_start = start,
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.range_end = end,
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};
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if (!mapping_cap_writeback_dirty(mapping))
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return 0;
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ret = do_writepages(mapping, &wbc);
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return ret;
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}
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static inline int __filemap_fdatawrite(struct address_space *mapping,
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int sync_mode)
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{
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return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
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}
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int filemap_fdatawrite(struct address_space *mapping)
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{
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return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
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}
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EXPORT_SYMBOL(filemap_fdatawrite);
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int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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loff_t end)
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{
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return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
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}
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EXPORT_SYMBOL(filemap_fdatawrite_range);
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/**
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* filemap_flush - mostly a non-blocking flush
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* @mapping: target address_space
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*
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* This is a mostly non-blocking flush. Not suitable for data-integrity
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* purposes - I/O may not be started against all dirty pages.
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*/
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int filemap_flush(struct address_space *mapping)
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{
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return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
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}
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EXPORT_SYMBOL(filemap_flush);
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/**
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* filemap_fdatawait_range - wait for writeback to complete
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* @mapping: address space structure to wait for
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* @start_byte: offset in bytes where the range starts
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* @end_byte: offset in bytes where the range ends (inclusive)
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*
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* Walk the list of under-writeback pages of the given address space
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* in the given range and wait for all of them.
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*/
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int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
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loff_t end_byte)
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{
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pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
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pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
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struct pagevec pvec;
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int nr_pages;
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int ret2, ret = 0;
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if (end_byte < start_byte)
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goto out;
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pagevec_init(&pvec, 0);
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while ((index <= end) &&
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(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
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PAGECACHE_TAG_WRITEBACK,
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min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
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unsigned i;
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for (i = 0; i < nr_pages; i++) {
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struct page *page = pvec.pages[i];
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/* until radix tree lookup accepts end_index */
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if (page->index > end)
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continue;
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wait_on_page_writeback(page);
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if (TestClearPageError(page))
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ret = -EIO;
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}
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pagevec_release(&pvec);
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cond_resched();
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}
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out:
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ret2 = filemap_check_errors(mapping);
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if (!ret)
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ret = ret2;
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return ret;
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}
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EXPORT_SYMBOL(filemap_fdatawait_range);
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/**
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* filemap_fdatawait - wait for all under-writeback pages to complete
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* @mapping: address space structure to wait for
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*
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* Walk the list of under-writeback pages of the given address space
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* and wait for all of them.
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*/
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int filemap_fdatawait(struct address_space *mapping)
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{
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loff_t i_size = i_size_read(mapping->host);
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if (i_size == 0)
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return 0;
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return filemap_fdatawait_range(mapping, 0, i_size - 1);
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}
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EXPORT_SYMBOL(filemap_fdatawait);
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int filemap_write_and_wait(struct address_space *mapping)
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{
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int err = 0;
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if (mapping->nrpages) {
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err = filemap_fdatawrite(mapping);
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/*
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* Even if the above returned error, the pages may be
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* written partially (e.g. -ENOSPC), so we wait for it.
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* But the -EIO is special case, it may indicate the worst
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* thing (e.g. bug) happened, so we avoid waiting for it.
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*/
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if (err != -EIO) {
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int err2 = filemap_fdatawait(mapping);
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if (!err)
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err = err2;
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}
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} else {
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err = filemap_check_errors(mapping);
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}
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return err;
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}
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EXPORT_SYMBOL(filemap_write_and_wait);
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/**
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* filemap_write_and_wait_range - write out & wait on a file range
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* @mapping: the address_space for the pages
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* @lstart: offset in bytes where the range starts
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* @lend: offset in bytes where the range ends (inclusive)
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*
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* Write out and wait upon file offsets lstart->lend, inclusive.
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*
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* Note that `lend' is inclusive (describes the last byte to be written) so
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* that this function can be used to write to the very end-of-file (end = -1).
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*/
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int filemap_write_and_wait_range(struct address_space *mapping,
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loff_t lstart, loff_t lend)
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{
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int err = 0;
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if (mapping->nrpages) {
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err = __filemap_fdatawrite_range(mapping, lstart, lend,
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WB_SYNC_ALL);
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/* See comment of filemap_write_and_wait() */
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if (err != -EIO) {
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int err2 = filemap_fdatawait_range(mapping,
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lstart, lend);
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if (!err)
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err = err2;
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}
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} else {
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err = filemap_check_errors(mapping);
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}
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return err;
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}
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EXPORT_SYMBOL(filemap_write_and_wait_range);
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|
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/**
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* replace_page_cache_page - replace a pagecache page with a new one
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* @old: page to be replaced
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* @new: page to replace with
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* @gfp_mask: allocation mode
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*
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* This function replaces a page in the pagecache with a new one. On
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* success it acquires the pagecache reference for the new page and
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* drops it for the old page. Both the old and new pages must be
|
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* locked. This function does not add the new page to the LRU, the
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* caller must do that.
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*
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* The remove + add is atomic. The only way this function can fail is
|
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* memory allocation failure.
|
|
*/
|
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int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
|
|
{
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int error;
|
|
|
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VM_BUG_ON(!PageLocked(old));
|
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VM_BUG_ON(!PageLocked(new));
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VM_BUG_ON(new->mapping);
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|
|
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error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
|
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if (!error) {
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struct address_space *mapping = old->mapping;
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void (*freepage)(struct page *);
|
|
|
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pgoff_t offset = old->index;
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freepage = mapping->a_ops->freepage;
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|
|
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page_cache_get(new);
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new->mapping = mapping;
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new->index = offset;
|
|
|
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spin_lock_irq(&mapping->tree_lock);
|
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__delete_from_page_cache(old);
|
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error = radix_tree_insert(&mapping->page_tree, offset, new);
|
|
BUG_ON(error);
|
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mapping->nrpages++;
|
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__inc_zone_page_state(new, NR_FILE_PAGES);
|
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if (PageSwapBacked(new))
|
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__inc_zone_page_state(new, NR_SHMEM);
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spin_unlock_irq(&mapping->tree_lock);
|
|
/* mem_cgroup codes must not be called under tree_lock */
|
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mem_cgroup_replace_page_cache(old, new);
|
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radix_tree_preload_end();
|
|
if (freepage)
|
|
freepage(old);
|
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page_cache_release(old);
|
|
}
|
|
|
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return error;
|
|
}
|
|
EXPORT_SYMBOL_GPL(replace_page_cache_page);
|
|
|
|
/**
|
|
* add_to_page_cache_locked - add a locked page to the pagecache
|
|
* @page: page to add
|
|
* @mapping: the page's address_space
|
|
* @offset: page index
|
|
* @gfp_mask: page allocation mode
|
|
*
|
|
* This function is used to add a page to the pagecache. It must be locked.
|
|
* This function does not add the page to the LRU. The caller must do that.
|
|
*/
|
|
int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
|
|
pgoff_t offset, gfp_t gfp_mask)
|
|
{
|
|
int error;
|
|
|
|
VM_BUG_ON(!PageLocked(page));
|
|
VM_BUG_ON(PageSwapBacked(page));
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|
|
|
error = mem_cgroup_cache_charge(page, current->mm,
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gfp_mask & GFP_RECLAIM_MASK);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
|
|
if (error == 0) {
|
|
page_cache_get(page);
|
|
page->mapping = mapping;
|
|
page->index = offset;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
error = radix_tree_insert(&mapping->page_tree, offset, page);
|
|
if (likely(!error)) {
|
|
mapping->nrpages++;
|
|
__inc_zone_page_state(page, NR_FILE_PAGES);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
trace_mm_filemap_add_to_page_cache(page);
|
|
} else {
|
|
page->mapping = NULL;
|
|
/* Leave page->index set: truncation relies upon it */
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
mem_cgroup_uncharge_cache_page(page);
|
|
page_cache_release(page);
|
|
}
|
|
radix_tree_preload_end();
|
|
} else
|
|
mem_cgroup_uncharge_cache_page(page);
|
|
out:
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(add_to_page_cache_locked);
|
|
|
|
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
|
|
pgoff_t offset, gfp_t gfp_mask)
|
|
{
|
|
int ret;
|
|
|
|
ret = add_to_page_cache(page, mapping, offset, gfp_mask);
|
|
if (ret == 0)
|
|
lru_cache_add_file(page);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
|
|
|
|
#ifdef CONFIG_NUMA
|
|
struct page *__page_cache_alloc(gfp_t gfp)
|
|
{
|
|
int n;
|
|
struct page *page;
|
|
|
|
if (cpuset_do_page_mem_spread()) {
|
|
unsigned int cpuset_mems_cookie;
|
|
do {
|
|
cpuset_mems_cookie = get_mems_allowed();
|
|
n = cpuset_mem_spread_node();
|
|
page = alloc_pages_exact_node(n, gfp, 0);
|
|
} while (!put_mems_allowed(cpuset_mems_cookie) && !page);
|
|
|
|
return page;
|
|
}
|
|
return alloc_pages(gfp, 0);
|
|
}
|
|
EXPORT_SYMBOL(__page_cache_alloc);
|
|
#endif
|
|
|
|
/*
|
|
* In order to wait for pages to become available there must be
|
|
* waitqueues associated with pages. By using a hash table of
|
|
* waitqueues where the bucket discipline is to maintain all
|
|
* waiters on the same queue and wake all when any of the pages
|
|
* become available, and for the woken contexts to check to be
|
|
* sure the appropriate page became available, this saves space
|
|
* at a cost of "thundering herd" phenomena during rare hash
|
|
* collisions.
|
|
*/
|
|
static wait_queue_head_t *page_waitqueue(struct page *page)
|
|
{
|
|
const struct zone *zone = page_zone(page);
|
|
|
|
return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
|
|
}
|
|
|
|
static inline void wake_up_page(struct page *page, int bit)
|
|
{
|
|
__wake_up_bit(page_waitqueue(page), &page->flags, bit);
|
|
}
|
|
|
|
void wait_on_page_bit(struct page *page, int bit_nr)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
|
|
|
if (test_bit(bit_nr, &page->flags))
|
|
__wait_on_bit(page_waitqueue(page), &wait, sleep_on_page,
|
|
TASK_UNINTERRUPTIBLE);
|
|
}
|
|
EXPORT_SYMBOL(wait_on_page_bit);
|
|
|
|
int wait_on_page_bit_killable(struct page *page, int bit_nr)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
|
|
|
if (!test_bit(bit_nr, &page->flags))
|
|
return 0;
|
|
|
|
return __wait_on_bit(page_waitqueue(page), &wait,
|
|
sleep_on_page_killable, TASK_KILLABLE);
|
|
}
|
|
|
|
/**
|
|
* add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
|
|
* @page: Page defining the wait queue of interest
|
|
* @waiter: Waiter to add to the queue
|
|
*
|
|
* Add an arbitrary @waiter to the wait queue for the nominated @page.
|
|
*/
|
|
void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
|
|
{
|
|
wait_queue_head_t *q = page_waitqueue(page);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&q->lock, flags);
|
|
__add_wait_queue(q, waiter);
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_page_wait_queue);
|
|
|
|
/**
|
|
* unlock_page - unlock a locked page
|
|
* @page: the page
|
|
*
|
|
* Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
|
|
* Also wakes sleepers in wait_on_page_writeback() because the wakeup
|
|
* mechananism between PageLocked pages and PageWriteback pages is shared.
|
|
* But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
|
|
*
|
|
* The mb is necessary to enforce ordering between the clear_bit and the read
|
|
* of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
|
|
*/
|
|
void unlock_page(struct page *page)
|
|
{
|
|
VM_BUG_ON(!PageLocked(page));
|
|
clear_bit_unlock(PG_locked, &page->flags);
|
|
smp_mb__after_clear_bit();
|
|
wake_up_page(page, PG_locked);
|
|
}
|
|
EXPORT_SYMBOL(unlock_page);
|
|
|
|
/**
|
|
* end_page_writeback - end writeback against a page
|
|
* @page: the page
|
|
*/
|
|
void end_page_writeback(struct page *page)
|
|
{
|
|
if (TestClearPageReclaim(page))
|
|
rotate_reclaimable_page(page);
|
|
|
|
if (!test_clear_page_writeback(page))
|
|
BUG();
|
|
|
|
smp_mb__after_clear_bit();
|
|
wake_up_page(page, PG_writeback);
|
|
}
|
|
EXPORT_SYMBOL(end_page_writeback);
|
|
|
|
/**
|
|
* __lock_page - get a lock on the page, assuming we need to sleep to get it
|
|
* @page: the page to lock
|
|
*/
|
|
void __lock_page(struct page *page)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
|
|
|
__wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page,
|
|
TASK_UNINTERRUPTIBLE);
|
|
}
|
|
EXPORT_SYMBOL(__lock_page);
|
|
|
|
int __lock_page_killable(struct page *page)
|
|
{
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
|
|
|
return __wait_on_bit_lock(page_waitqueue(page), &wait,
|
|
sleep_on_page_killable, TASK_KILLABLE);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__lock_page_killable);
|
|
|
|
int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
|
|
unsigned int flags)
|
|
{
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
/*
|
|
* CAUTION! In this case, mmap_sem is not released
|
|
* even though return 0.
|
|
*/
|
|
if (flags & FAULT_FLAG_RETRY_NOWAIT)
|
|
return 0;
|
|
|
|
up_read(&mm->mmap_sem);
|
|
if (flags & FAULT_FLAG_KILLABLE)
|
|
wait_on_page_locked_killable(page);
|
|
else
|
|
wait_on_page_locked(page);
|
|
return 0;
|
|
} else {
|
|
if (flags & FAULT_FLAG_KILLABLE) {
|
|
int ret;
|
|
|
|
ret = __lock_page_killable(page);
|
|
if (ret) {
|
|
up_read(&mm->mmap_sem);
|
|
return 0;
|
|
}
|
|
} else
|
|
__lock_page(page);
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* find_get_page - find and get a page reference
|
|
* @mapping: the address_space to search
|
|
* @offset: the page index
|
|
*
|
|
* Is there a pagecache struct page at the given (mapping, offset) tuple?
|
|
* If yes, increment its refcount and return it; if no, return NULL.
|
|
*/
|
|
struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
|
|
{
|
|
void **pagep;
|
|
struct page *page;
|
|
|
|
rcu_read_lock();
|
|
repeat:
|
|
page = NULL;
|
|
pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
|
|
if (pagep) {
|
|
page = radix_tree_deref_slot(pagep);
|
|
if (unlikely(!page))
|
|
goto out;
|
|
if (radix_tree_exception(page)) {
|
|
if (radix_tree_deref_retry(page))
|
|
goto repeat;
|
|
/*
|
|
* Otherwise, shmem/tmpfs must be storing a swap entry
|
|
* here as an exceptional entry: so return it without
|
|
* attempting to raise page count.
|
|
*/
|
|
goto out;
|
|
}
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/*
|
|
* Has the page moved?
|
|
* This is part of the lockless pagecache protocol. See
|
|
* include/linux/pagemap.h for details.
|
|
*/
|
|
if (unlikely(page != *pagep)) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
}
|
|
out:
|
|
rcu_read_unlock();
|
|
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(find_get_page);
|
|
|
|
/**
|
|
* find_lock_page - locate, pin and lock a pagecache page
|
|
* @mapping: the address_space to search
|
|
* @offset: the page index
|
|
*
|
|
* Locates the desired pagecache page, locks it, increments its reference
|
|
* count and returns its address.
|
|
*
|
|
* Returns zero if the page was not present. find_lock_page() may sleep.
|
|
*/
|
|
struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
|
|
{
|
|
struct page *page;
|
|
|
|
repeat:
|
|
page = find_get_page(mapping, offset);
|
|
if (page && !radix_tree_exception(page)) {
|
|
lock_page(page);
|
|
/* Has the page been truncated? */
|
|
if (unlikely(page->mapping != mapping)) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
VM_BUG_ON(page->index != offset);
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(find_lock_page);
|
|
|
|
/**
|
|
* find_or_create_page - locate or add a pagecache page
|
|
* @mapping: the page's address_space
|
|
* @index: the page's index into the mapping
|
|
* @gfp_mask: page allocation mode
|
|
*
|
|
* Locates a page in the pagecache. If the page is not present, a new page
|
|
* is allocated using @gfp_mask and is added to the pagecache and to the VM's
|
|
* LRU list. The returned page is locked and has its reference count
|
|
* incremented.
|
|
*
|
|
* find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
|
|
* allocation!
|
|
*
|
|
* find_or_create_page() returns the desired page's address, or zero on
|
|
* memory exhaustion.
|
|
*/
|
|
struct page *find_or_create_page(struct address_space *mapping,
|
|
pgoff_t index, gfp_t gfp_mask)
|
|
{
|
|
struct page *page;
|
|
int err;
|
|
repeat:
|
|
page = find_lock_page(mapping, index);
|
|
if (!page) {
|
|
page = __page_cache_alloc(gfp_mask);
|
|
if (!page)
|
|
return NULL;
|
|
/*
|
|
* We want a regular kernel memory (not highmem or DMA etc)
|
|
* allocation for the radix tree nodes, but we need to honour
|
|
* the context-specific requirements the caller has asked for.
|
|
* GFP_RECLAIM_MASK collects those requirements.
|
|
*/
|
|
err = add_to_page_cache_lru(page, mapping, index,
|
|
(gfp_mask & GFP_RECLAIM_MASK));
|
|
if (unlikely(err)) {
|
|
page_cache_release(page);
|
|
page = NULL;
|
|
if (err == -EEXIST)
|
|
goto repeat;
|
|
}
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(find_or_create_page);
|
|
|
|
/**
|
|
* find_get_pages - gang pagecache lookup
|
|
* @mapping: The address_space to search
|
|
* @start: The starting page index
|
|
* @nr_pages: The maximum number of pages
|
|
* @pages: Where the resulting pages are placed
|
|
*
|
|
* find_get_pages() will search for and return a group of up to
|
|
* @nr_pages pages in the mapping. The pages are placed at @pages.
|
|
* find_get_pages() takes a reference against the returned pages.
|
|
*
|
|
* The search returns a group of mapping-contiguous pages with ascending
|
|
* indexes. There may be holes in the indices due to not-present pages.
|
|
*
|
|
* find_get_pages() returns the number of pages which were found.
|
|
*/
|
|
unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
|
|
unsigned int nr_pages, struct page **pages)
|
|
{
|
|
struct radix_tree_iter iter;
|
|
void **slot;
|
|
unsigned ret = 0;
|
|
|
|
if (unlikely(!nr_pages))
|
|
return 0;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
|
|
struct page *page;
|
|
repeat:
|
|
page = radix_tree_deref_slot(slot);
|
|
if (unlikely(!page))
|
|
continue;
|
|
|
|
if (radix_tree_exception(page)) {
|
|
if (radix_tree_deref_retry(page)) {
|
|
/*
|
|
* Transient condition which can only trigger
|
|
* when entry at index 0 moves out of or back
|
|
* to root: none yet gotten, safe to restart.
|
|
*/
|
|
WARN_ON(iter.index);
|
|
goto restart;
|
|
}
|
|
/*
|
|
* Otherwise, shmem/tmpfs must be storing a swap entry
|
|
* here as an exceptional entry: so skip over it -
|
|
* we only reach this from invalidate_mapping_pages().
|
|
*/
|
|
continue;
|
|
}
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/* Has the page moved? */
|
|
if (unlikely(page != *slot)) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
|
|
pages[ret] = page;
|
|
if (++ret == nr_pages)
|
|
break;
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* find_get_pages_contig - gang contiguous pagecache lookup
|
|
* @mapping: The address_space to search
|
|
* @index: The starting page index
|
|
* @nr_pages: The maximum number of pages
|
|
* @pages: Where the resulting pages are placed
|
|
*
|
|
* find_get_pages_contig() works exactly like find_get_pages(), except
|
|
* that the returned number of pages are guaranteed to be contiguous.
|
|
*
|
|
* find_get_pages_contig() returns the number of pages which were found.
|
|
*/
|
|
unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
|
|
unsigned int nr_pages, struct page **pages)
|
|
{
|
|
struct radix_tree_iter iter;
|
|
void **slot;
|
|
unsigned int ret = 0;
|
|
|
|
if (unlikely(!nr_pages))
|
|
return 0;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
|
|
struct page *page;
|
|
repeat:
|
|
page = radix_tree_deref_slot(slot);
|
|
/* The hole, there no reason to continue */
|
|
if (unlikely(!page))
|
|
break;
|
|
|
|
if (radix_tree_exception(page)) {
|
|
if (radix_tree_deref_retry(page)) {
|
|
/*
|
|
* Transient condition which can only trigger
|
|
* when entry at index 0 moves out of or back
|
|
* to root: none yet gotten, safe to restart.
|
|
*/
|
|
goto restart;
|
|
}
|
|
/*
|
|
* Otherwise, shmem/tmpfs must be storing a swap entry
|
|
* here as an exceptional entry: so stop looking for
|
|
* contiguous pages.
|
|
*/
|
|
break;
|
|
}
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/* Has the page moved? */
|
|
if (unlikely(page != *slot)) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
|
|
/*
|
|
* must check mapping and index after taking the ref.
|
|
* otherwise we can get both false positives and false
|
|
* negatives, which is just confusing to the caller.
|
|
*/
|
|
if (page->mapping == NULL || page->index != iter.index) {
|
|
page_cache_release(page);
|
|
break;
|
|
}
|
|
|
|
pages[ret] = page;
|
|
if (++ret == nr_pages)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(find_get_pages_contig);
|
|
|
|
/**
|
|
* find_get_pages_tag - find and return pages that match @tag
|
|
* @mapping: the address_space to search
|
|
* @index: the starting page index
|
|
* @tag: the tag index
|
|
* @nr_pages: the maximum number of pages
|
|
* @pages: where the resulting pages are placed
|
|
*
|
|
* Like find_get_pages, except we only return pages which are tagged with
|
|
* @tag. We update @index to index the next page for the traversal.
|
|
*/
|
|
unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
|
|
int tag, unsigned int nr_pages, struct page **pages)
|
|
{
|
|
struct radix_tree_iter iter;
|
|
void **slot;
|
|
unsigned ret = 0;
|
|
|
|
if (unlikely(!nr_pages))
|
|
return 0;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
radix_tree_for_each_tagged(slot, &mapping->page_tree,
|
|
&iter, *index, tag) {
|
|
struct page *page;
|
|
repeat:
|
|
page = radix_tree_deref_slot(slot);
|
|
if (unlikely(!page))
|
|
continue;
|
|
|
|
if (radix_tree_exception(page)) {
|
|
if (radix_tree_deref_retry(page)) {
|
|
/*
|
|
* Transient condition which can only trigger
|
|
* when entry at index 0 moves out of or back
|
|
* to root: none yet gotten, safe to restart.
|
|
*/
|
|
goto restart;
|
|
}
|
|
/*
|
|
* This function is never used on a shmem/tmpfs
|
|
* mapping, so a swap entry won't be found here.
|
|
*/
|
|
BUG();
|
|
}
|
|
|
|
if (!page_cache_get_speculative(page))
|
|
goto repeat;
|
|
|
|
/* Has the page moved? */
|
|
if (unlikely(page != *slot)) {
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
|
|
pages[ret] = page;
|
|
if (++ret == nr_pages)
|
|
break;
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
|
|
if (ret)
|
|
*index = pages[ret - 1]->index + 1;
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(find_get_pages_tag);
|
|
|
|
/**
|
|
* grab_cache_page_nowait - returns locked page at given index in given cache
|
|
* @mapping: target address_space
|
|
* @index: the page index
|
|
*
|
|
* Same as grab_cache_page(), but do not wait if the page is unavailable.
|
|
* This is intended for speculative data generators, where the data can
|
|
* be regenerated if the page couldn't be grabbed. This routine should
|
|
* be safe to call while holding the lock for another page.
|
|
*
|
|
* Clear __GFP_FS when allocating the page to avoid recursion into the fs
|
|
* and deadlock against the caller's locked page.
|
|
*/
|
|
struct page *
|
|
grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
struct page *page = find_get_page(mapping, index);
|
|
|
|
if (page) {
|
|
if (trylock_page(page))
|
|
return page;
|
|
page_cache_release(page);
|
|
return NULL;
|
|
}
|
|
page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
|
|
if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
|
|
page_cache_release(page);
|
|
page = NULL;
|
|
}
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(grab_cache_page_nowait);
|
|
|
|
/*
|
|
* CD/DVDs are error prone. When a medium error occurs, the driver may fail
|
|
* a _large_ part of the i/o request. Imagine the worst scenario:
|
|
*
|
|
* ---R__________________________________________B__________
|
|
* ^ reading here ^ bad block(assume 4k)
|
|
*
|
|
* read(R) => miss => readahead(R...B) => media error => frustrating retries
|
|
* => failing the whole request => read(R) => read(R+1) =>
|
|
* readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
|
|
* readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
|
|
* readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
|
|
*
|
|
* It is going insane. Fix it by quickly scaling down the readahead size.
|
|
*/
|
|
static void shrink_readahead_size_eio(struct file *filp,
|
|
struct file_ra_state *ra)
|
|
{
|
|
ra->ra_pages /= 4;
|
|
}
|
|
|
|
/**
|
|
* do_generic_file_read - generic file read routine
|
|
* @filp: the file to read
|
|
* @ppos: current file position
|
|
* @desc: read_descriptor
|
|
* @actor: read method
|
|
*
|
|
* This is a generic file read routine, and uses the
|
|
* mapping->a_ops->readpage() function for the actual low-level stuff.
|
|
*
|
|
* This is really ugly. But the goto's actually try to clarify some
|
|
* of the logic when it comes to error handling etc.
|
|
*/
|
|
static void do_generic_file_read(struct file *filp, loff_t *ppos,
|
|
read_descriptor_t *desc, read_actor_t actor)
|
|
{
|
|
struct address_space *mapping = filp->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
struct file_ra_state *ra = &filp->f_ra;
|
|
pgoff_t index;
|
|
pgoff_t last_index;
|
|
pgoff_t prev_index;
|
|
unsigned long offset; /* offset into pagecache page */
|
|
unsigned int prev_offset;
|
|
int error;
|
|
|
|
index = *ppos >> PAGE_CACHE_SHIFT;
|
|
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
|
|
prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
|
|
last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
|
|
offset = *ppos & ~PAGE_CACHE_MASK;
|
|
|
|
for (;;) {
|
|
struct page *page;
|
|
pgoff_t end_index;
|
|
loff_t isize;
|
|
unsigned long nr, ret;
|
|
|
|
cond_resched();
|
|
find_page:
|
|
page = find_get_page(mapping, index);
|
|
if (!page) {
|
|
page_cache_sync_readahead(mapping,
|
|
ra, filp,
|
|
index, last_index - index);
|
|
page = find_get_page(mapping, index);
|
|
if (unlikely(page == NULL))
|
|
goto no_cached_page;
|
|
}
|
|
if (PageReadahead(page)) {
|
|
page_cache_async_readahead(mapping,
|
|
ra, filp, page,
|
|
index, last_index - index);
|
|
}
|
|
if (!PageUptodate(page)) {
|
|
if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
|
|
!mapping->a_ops->is_partially_uptodate)
|
|
goto page_not_up_to_date;
|
|
if (!trylock_page(page))
|
|
goto page_not_up_to_date;
|
|
/* Did it get truncated before we got the lock? */
|
|
if (!page->mapping)
|
|
goto page_not_up_to_date_locked;
|
|
if (!mapping->a_ops->is_partially_uptodate(page,
|
|
desc, offset))
|
|
goto page_not_up_to_date_locked;
|
|
unlock_page(page);
|
|
}
|
|
page_ok:
|
|
/*
|
|
* i_size must be checked after we know the page is Uptodate.
|
|
*
|
|
* Checking i_size after the check allows us to calculate
|
|
* the correct value for "nr", which means the zero-filled
|
|
* part of the page is not copied back to userspace (unless
|
|
* another truncate extends the file - this is desired though).
|
|
*/
|
|
|
|
isize = i_size_read(inode);
|
|
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
|
|
if (unlikely(!isize || index > end_index)) {
|
|
page_cache_release(page);
|
|
goto out;
|
|
}
|
|
|
|
/* nr is the maximum number of bytes to copy from this page */
|
|
nr = PAGE_CACHE_SIZE;
|
|
if (index == end_index) {
|
|
nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
|
|
if (nr <= offset) {
|
|
page_cache_release(page);
|
|
goto out;
|
|
}
|
|
}
|
|
nr = nr - offset;
|
|
|
|
/* If users can be writing to this page using arbitrary
|
|
* virtual addresses, take care about potential aliasing
|
|
* before reading the page on the kernel side.
|
|
*/
|
|
if (mapping_writably_mapped(mapping))
|
|
flush_dcache_page(page);
|
|
|
|
/*
|
|
* When a sequential read accesses a page several times,
|
|
* only mark it as accessed the first time.
|
|
*/
|
|
if (prev_index != index || offset != prev_offset)
|
|
mark_page_accessed(page);
|
|
prev_index = index;
|
|
|
|
/*
|
|
* Ok, we have the page, and it's up-to-date, so
|
|
* now we can copy it to user space...
|
|
*
|
|
* The actor routine returns how many bytes were actually used..
|
|
* NOTE! This may not be the same as how much of a user buffer
|
|
* we filled up (we may be padding etc), so we can only update
|
|
* "pos" here (the actor routine has to update the user buffer
|
|
* pointers and the remaining count).
|
|
*/
|
|
ret = actor(desc, page, offset, nr);
|
|
offset += ret;
|
|
index += offset >> PAGE_CACHE_SHIFT;
|
|
offset &= ~PAGE_CACHE_MASK;
|
|
prev_offset = offset;
|
|
|
|
page_cache_release(page);
|
|
if (ret == nr && desc->count)
|
|
continue;
|
|
goto out;
|
|
|
|
page_not_up_to_date:
|
|
/* Get exclusive access to the page ... */
|
|
error = lock_page_killable(page);
|
|
if (unlikely(error))
|
|
goto readpage_error;
|
|
|
|
page_not_up_to_date_locked:
|
|
/* Did it get truncated before we got the lock? */
|
|
if (!page->mapping) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
continue;
|
|
}
|
|
|
|
/* Did somebody else fill it already? */
|
|
if (PageUptodate(page)) {
|
|
unlock_page(page);
|
|
goto page_ok;
|
|
}
|
|
|
|
readpage:
|
|
/*
|
|
* A previous I/O error may have been due to temporary
|
|
* failures, eg. multipath errors.
|
|
* PG_error will be set again if readpage fails.
|
|
*/
|
|
ClearPageError(page);
|
|
/* Start the actual read. The read will unlock the page. */
|
|
error = mapping->a_ops->readpage(filp, page);
|
|
|
|
if (unlikely(error)) {
|
|
if (error == AOP_TRUNCATED_PAGE) {
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
}
|
|
goto readpage_error;
|
|
}
|
|
|
|
if (!PageUptodate(page)) {
|
|
error = lock_page_killable(page);
|
|
if (unlikely(error))
|
|
goto readpage_error;
|
|
if (!PageUptodate(page)) {
|
|
if (page->mapping == NULL) {
|
|
/*
|
|
* invalidate_mapping_pages got it
|
|
*/
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
}
|
|
unlock_page(page);
|
|
shrink_readahead_size_eio(filp, ra);
|
|
error = -EIO;
|
|
goto readpage_error;
|
|
}
|
|
unlock_page(page);
|
|
}
|
|
|
|
goto page_ok;
|
|
|
|
readpage_error:
|
|
/* UHHUH! A synchronous read error occurred. Report it */
|
|
desc->error = error;
|
|
page_cache_release(page);
|
|
goto out;
|
|
|
|
no_cached_page:
|
|
/*
|
|
* Ok, it wasn't cached, so we need to create a new
|
|
* page..
|
|
*/
|
|
page = page_cache_alloc_cold(mapping);
|
|
if (!page) {
|
|
desc->error = -ENOMEM;
|
|
goto out;
|
|
}
|
|
error = add_to_page_cache_lru(page, mapping,
|
|
index, GFP_KERNEL);
|
|
if (error) {
|
|
page_cache_release(page);
|
|
if (error == -EEXIST)
|
|
goto find_page;
|
|
desc->error = error;
|
|
goto out;
|
|
}
|
|
goto readpage;
|
|
}
|
|
|
|
out:
|
|
ra->prev_pos = prev_index;
|
|
ra->prev_pos <<= PAGE_CACHE_SHIFT;
|
|
ra->prev_pos |= prev_offset;
|
|
|
|
*ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
|
|
file_accessed(filp);
|
|
}
|
|
|
|
int file_read_actor(read_descriptor_t *desc, struct page *page,
|
|
unsigned long offset, unsigned long size)
|
|
{
|
|
char *kaddr;
|
|
unsigned long left, count = desc->count;
|
|
|
|
if (size > count)
|
|
size = count;
|
|
|
|
/*
|
|
* Faults on the destination of a read are common, so do it before
|
|
* taking the kmap.
|
|
*/
|
|
if (!fault_in_pages_writeable(desc->arg.buf, size)) {
|
|
kaddr = kmap_atomic(page);
|
|
left = __copy_to_user_inatomic(desc->arg.buf,
|
|
kaddr + offset, size);
|
|
kunmap_atomic(kaddr);
|
|
if (left == 0)
|
|
goto success;
|
|
}
|
|
|
|
/* Do it the slow way */
|
|
kaddr = kmap(page);
|
|
left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
|
|
kunmap(page);
|
|
|
|
if (left) {
|
|
size -= left;
|
|
desc->error = -EFAULT;
|
|
}
|
|
success:
|
|
desc->count = count - size;
|
|
desc->written += size;
|
|
desc->arg.buf += size;
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* Performs necessary checks before doing a write
|
|
* @iov: io vector request
|
|
* @nr_segs: number of segments in the iovec
|
|
* @count: number of bytes to write
|
|
* @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
|
|
*
|
|
* Adjust number of segments and amount of bytes to write (nr_segs should be
|
|
* properly initialized first). Returns appropriate error code that caller
|
|
* should return or zero in case that write should be allowed.
|
|
*/
|
|
int generic_segment_checks(const struct iovec *iov,
|
|
unsigned long *nr_segs, size_t *count, int access_flags)
|
|
{
|
|
unsigned long seg;
|
|
size_t cnt = 0;
|
|
for (seg = 0; seg < *nr_segs; seg++) {
|
|
const struct iovec *iv = &iov[seg];
|
|
|
|
/*
|
|
* If any segment has a negative length, or the cumulative
|
|
* length ever wraps negative then return -EINVAL.
|
|
*/
|
|
cnt += iv->iov_len;
|
|
if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
|
|
return -EINVAL;
|
|
if (access_ok(access_flags, iv->iov_base, iv->iov_len))
|
|
continue;
|
|
if (seg == 0)
|
|
return -EFAULT;
|
|
*nr_segs = seg;
|
|
cnt -= iv->iov_len; /* This segment is no good */
|
|
break;
|
|
}
|
|
*count = cnt;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(generic_segment_checks);
|
|
|
|
/**
|
|
* generic_file_aio_read - generic filesystem read routine
|
|
* @iocb: kernel I/O control block
|
|
* @iov: io vector request
|
|
* @nr_segs: number of segments in the iovec
|
|
* @pos: current file position
|
|
*
|
|
* This is the "read()" routine for all filesystems
|
|
* that can use the page cache directly.
|
|
*/
|
|
ssize_t
|
|
generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos)
|
|
{
|
|
struct file *filp = iocb->ki_filp;
|
|
ssize_t retval;
|
|
unsigned long seg = 0;
|
|
size_t count;
|
|
loff_t *ppos = &iocb->ki_pos;
|
|
|
|
count = 0;
|
|
retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
|
|
if (retval)
|
|
return retval;
|
|
|
|
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
|
|
if (filp->f_flags & O_DIRECT) {
|
|
loff_t size;
|
|
struct address_space *mapping;
|
|
struct inode *inode;
|
|
|
|
mapping = filp->f_mapping;
|
|
inode = mapping->host;
|
|
if (!count)
|
|
goto out; /* skip atime */
|
|
size = i_size_read(inode);
|
|
if (pos < size) {
|
|
retval = filemap_write_and_wait_range(mapping, pos,
|
|
pos + iov_length(iov, nr_segs) - 1);
|
|
if (!retval) {
|
|
retval = mapping->a_ops->direct_IO(READ, iocb,
|
|
iov, pos, nr_segs);
|
|
}
|
|
if (retval > 0) {
|
|
*ppos = pos + retval;
|
|
count -= retval;
|
|
}
|
|
|
|
/*
|
|
* Btrfs can have a short DIO read if we encounter
|
|
* compressed extents, so if there was an error, or if
|
|
* we've already read everything we wanted to, or if
|
|
* there was a short read because we hit EOF, go ahead
|
|
* and return. Otherwise fallthrough to buffered io for
|
|
* the rest of the read.
|
|
*/
|
|
if (retval < 0 || !count || *ppos >= size) {
|
|
file_accessed(filp);
|
|
goto out;
|
|
}
|
|
}
|
|
}
|
|
|
|
count = retval;
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
read_descriptor_t desc;
|
|
loff_t offset = 0;
|
|
|
|
/*
|
|
* If we did a short DIO read we need to skip the section of the
|
|
* iov that we've already read data into.
|
|
*/
|
|
if (count) {
|
|
if (count > iov[seg].iov_len) {
|
|
count -= iov[seg].iov_len;
|
|
continue;
|
|
}
|
|
offset = count;
|
|
count = 0;
|
|
}
|
|
|
|
desc.written = 0;
|
|
desc.arg.buf = iov[seg].iov_base + offset;
|
|
desc.count = iov[seg].iov_len - offset;
|
|
if (desc.count == 0)
|
|
continue;
|
|
desc.error = 0;
|
|
do_generic_file_read(filp, ppos, &desc, file_read_actor);
|
|
retval += desc.written;
|
|
if (desc.error) {
|
|
retval = retval ?: desc.error;
|
|
break;
|
|
}
|
|
if (desc.count > 0)
|
|
break;
|
|
}
|
|
out:
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_aio_read);
|
|
|
|
#ifdef CONFIG_MMU
|
|
/**
|
|
* page_cache_read - adds requested page to the page cache if not already there
|
|
* @file: file to read
|
|
* @offset: page index
|
|
*
|
|
* This adds the requested page to the page cache if it isn't already there,
|
|
* and schedules an I/O to read in its contents from disk.
|
|
*/
|
|
static int page_cache_read(struct file *file, pgoff_t offset)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct page *page;
|
|
int ret;
|
|
|
|
do {
|
|
page = page_cache_alloc_cold(mapping);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
|
|
if (ret == 0)
|
|
ret = mapping->a_ops->readpage(file, page);
|
|
else if (ret == -EEXIST)
|
|
ret = 0; /* losing race to add is OK */
|
|
|
|
page_cache_release(page);
|
|
|
|
} while (ret == AOP_TRUNCATED_PAGE);
|
|
|
|
return ret;
|
|
}
|
|
|
|
#define MMAP_LOTSAMISS (100)
|
|
|
|
/*
|
|
* Synchronous readahead happens when we don't even find
|
|
* a page in the page cache at all.
|
|
*/
|
|
static void do_sync_mmap_readahead(struct vm_area_struct *vma,
|
|
struct file_ra_state *ra,
|
|
struct file *file,
|
|
pgoff_t offset)
|
|
{
|
|
unsigned long ra_pages;
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
/* If we don't want any read-ahead, don't bother */
|
|
if (VM_RandomReadHint(vma))
|
|
return;
|
|
if (!ra->ra_pages)
|
|
return;
|
|
|
|
if (VM_SequentialReadHint(vma)) {
|
|
page_cache_sync_readahead(mapping, ra, file, offset,
|
|
ra->ra_pages);
|
|
return;
|
|
}
|
|
|
|
/* Avoid banging the cache line if not needed */
|
|
if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
|
|
ra->mmap_miss++;
|
|
|
|
/*
|
|
* Do we miss much more than hit in this file? If so,
|
|
* stop bothering with read-ahead. It will only hurt.
|
|
*/
|
|
if (ra->mmap_miss > MMAP_LOTSAMISS)
|
|
return;
|
|
|
|
/*
|
|
* mmap read-around
|
|
*/
|
|
ra_pages = max_sane_readahead(ra->ra_pages);
|
|
ra->start = max_t(long, 0, offset - ra_pages / 2);
|
|
ra->size = ra_pages;
|
|
ra->async_size = ra_pages / 4;
|
|
ra_submit(ra, mapping, file);
|
|
}
|
|
|
|
/*
|
|
* Asynchronous readahead happens when we find the page and PG_readahead,
|
|
* so we want to possibly extend the readahead further..
|
|
*/
|
|
static void do_async_mmap_readahead(struct vm_area_struct *vma,
|
|
struct file_ra_state *ra,
|
|
struct file *file,
|
|
struct page *page,
|
|
pgoff_t offset)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
/* If we don't want any read-ahead, don't bother */
|
|
if (VM_RandomReadHint(vma))
|
|
return;
|
|
if (ra->mmap_miss > 0)
|
|
ra->mmap_miss--;
|
|
if (PageReadahead(page))
|
|
page_cache_async_readahead(mapping, ra, file,
|
|
page, offset, ra->ra_pages);
|
|
}
|
|
|
|
/**
|
|
* filemap_fault - read in file data for page fault handling
|
|
* @vma: vma in which the fault was taken
|
|
* @vmf: struct vm_fault containing details of the fault
|
|
*
|
|
* filemap_fault() is invoked via the vma operations vector for a
|
|
* mapped memory region to read in file data during a page fault.
|
|
*
|
|
* The goto's are kind of ugly, but this streamlines the normal case of having
|
|
* it in the page cache, and handles the special cases reasonably without
|
|
* having a lot of duplicated code.
|
|
*/
|
|
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
int error;
|
|
struct file *file = vma->vm_file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct file_ra_state *ra = &file->f_ra;
|
|
struct inode *inode = mapping->host;
|
|
pgoff_t offset = vmf->pgoff;
|
|
struct page *page;
|
|
pgoff_t size;
|
|
int ret = 0;
|
|
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
if (offset >= size)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
/*
|
|
* Do we have something in the page cache already?
|
|
*/
|
|
page = find_get_page(mapping, offset);
|
|
if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
|
|
/*
|
|
* We found the page, so try async readahead before
|
|
* waiting for the lock.
|
|
*/
|
|
do_async_mmap_readahead(vma, ra, file, page, offset);
|
|
} else if (!page) {
|
|
/* No page in the page cache at all */
|
|
do_sync_mmap_readahead(vma, ra, file, offset);
|
|
count_vm_event(PGMAJFAULT);
|
|
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
|
|
ret = VM_FAULT_MAJOR;
|
|
retry_find:
|
|
page = find_get_page(mapping, offset);
|
|
if (!page)
|
|
goto no_cached_page;
|
|
}
|
|
|
|
if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
|
|
page_cache_release(page);
|
|
return ret | VM_FAULT_RETRY;
|
|
}
|
|
|
|
/* Did it get truncated? */
|
|
if (unlikely(page->mapping != mapping)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
goto retry_find;
|
|
}
|
|
VM_BUG_ON(page->index != offset);
|
|
|
|
/*
|
|
* We have a locked page in the page cache, now we need to check
|
|
* that it's up-to-date. If not, it is going to be due to an error.
|
|
*/
|
|
if (unlikely(!PageUptodate(page)))
|
|
goto page_not_uptodate;
|
|
|
|
/*
|
|
* Found the page and have a reference on it.
|
|
* We must recheck i_size under page lock.
|
|
*/
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
if (unlikely(offset >= size)) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
vmf->page = page;
|
|
return ret | VM_FAULT_LOCKED;
|
|
|
|
no_cached_page:
|
|
/*
|
|
* We're only likely to ever get here if MADV_RANDOM is in
|
|
* effect.
|
|
*/
|
|
error = page_cache_read(file, offset);
|
|
|
|
/*
|
|
* The page we want has now been added to the page cache.
|
|
* In the unlikely event that someone removed it in the
|
|
* meantime, we'll just come back here and read it again.
|
|
*/
|
|
if (error >= 0)
|
|
goto retry_find;
|
|
|
|
/*
|
|
* An error return from page_cache_read can result if the
|
|
* system is low on memory, or a problem occurs while trying
|
|
* to schedule I/O.
|
|
*/
|
|
if (error == -ENOMEM)
|
|
return VM_FAULT_OOM;
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
page_not_uptodate:
|
|
/*
|
|
* Umm, take care of errors if the page isn't up-to-date.
|
|
* Try to re-read it _once_. We do this synchronously,
|
|
* because there really aren't any performance issues here
|
|
* and we need to check for errors.
|
|
*/
|
|
ClearPageError(page);
|
|
error = mapping->a_ops->readpage(file, page);
|
|
if (!error) {
|
|
wait_on_page_locked(page);
|
|
if (!PageUptodate(page))
|
|
error = -EIO;
|
|
}
|
|
page_cache_release(page);
|
|
|
|
if (!error || error == AOP_TRUNCATED_PAGE)
|
|
goto retry_find;
|
|
|
|
/* Things didn't work out. Return zero to tell the mm layer so. */
|
|
shrink_readahead_size_eio(file, ra);
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
EXPORT_SYMBOL(filemap_fault);
|
|
|
|
int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
struct page *page = vmf->page;
|
|
struct inode *inode = file_inode(vma->vm_file);
|
|
int ret = VM_FAULT_LOCKED;
|
|
|
|
sb_start_pagefault(inode->i_sb);
|
|
file_update_time(vma->vm_file);
|
|
lock_page(page);
|
|
if (page->mapping != inode->i_mapping) {
|
|
unlock_page(page);
|
|
ret = VM_FAULT_NOPAGE;
|
|
goto out;
|
|
}
|
|
/*
|
|
* We mark the page dirty already here so that when freeze is in
|
|
* progress, we are guaranteed that writeback during freezing will
|
|
* see the dirty page and writeprotect it again.
|
|
*/
|
|
set_page_dirty(page);
|
|
wait_for_stable_page(page);
|
|
out:
|
|
sb_end_pagefault(inode->i_sb);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(filemap_page_mkwrite);
|
|
|
|
const struct vm_operations_struct generic_file_vm_ops = {
|
|
.fault = filemap_fault,
|
|
.page_mkwrite = filemap_page_mkwrite,
|
|
.remap_pages = generic_file_remap_pages,
|
|
};
|
|
|
|
/* This is used for a general mmap of a disk file */
|
|
|
|
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
if (!mapping->a_ops->readpage)
|
|
return -ENOEXEC;
|
|
file_accessed(file);
|
|
vma->vm_ops = &generic_file_vm_ops;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This is for filesystems which do not implement ->writepage.
|
|
*/
|
|
int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
|
|
return -EINVAL;
|
|
return generic_file_mmap(file, vma);
|
|
}
|
|
#else
|
|
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
#endif /* CONFIG_MMU */
|
|
|
|
EXPORT_SYMBOL(generic_file_mmap);
|
|
EXPORT_SYMBOL(generic_file_readonly_mmap);
|
|
|
|
static struct page *__read_cache_page(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *, struct page *),
|
|
void *data,
|
|
gfp_t gfp)
|
|
{
|
|
struct page *page;
|
|
int err;
|
|
repeat:
|
|
page = find_get_page(mapping, index);
|
|
if (!page) {
|
|
page = __page_cache_alloc(gfp | __GFP_COLD);
|
|
if (!page)
|
|
return ERR_PTR(-ENOMEM);
|
|
err = add_to_page_cache_lru(page, mapping, index, gfp);
|
|
if (unlikely(err)) {
|
|
page_cache_release(page);
|
|
if (err == -EEXIST)
|
|
goto repeat;
|
|
/* Presumably ENOMEM for radix tree node */
|
|
return ERR_PTR(err);
|
|
}
|
|
err = filler(data, page);
|
|
if (err < 0) {
|
|
page_cache_release(page);
|
|
page = ERR_PTR(err);
|
|
}
|
|
}
|
|
return page;
|
|
}
|
|
|
|
static struct page *do_read_cache_page(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *, struct page *),
|
|
void *data,
|
|
gfp_t gfp)
|
|
|
|
{
|
|
struct page *page;
|
|
int err;
|
|
|
|
retry:
|
|
page = __read_cache_page(mapping, index, filler, data, gfp);
|
|
if (IS_ERR(page))
|
|
return page;
|
|
if (PageUptodate(page))
|
|
goto out;
|
|
|
|
lock_page(page);
|
|
if (!page->mapping) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto retry;
|
|
}
|
|
if (PageUptodate(page)) {
|
|
unlock_page(page);
|
|
goto out;
|
|
}
|
|
err = filler(data, page);
|
|
if (err < 0) {
|
|
page_cache_release(page);
|
|
return ERR_PTR(err);
|
|
}
|
|
out:
|
|
mark_page_accessed(page);
|
|
return page;
|
|
}
|
|
|
|
/**
|
|
* read_cache_page_async - read into page cache, fill it if needed
|
|
* @mapping: the page's address_space
|
|
* @index: the page index
|
|
* @filler: function to perform the read
|
|
* @data: first arg to filler(data, page) function, often left as NULL
|
|
*
|
|
* Same as read_cache_page, but don't wait for page to become unlocked
|
|
* after submitting it to the filler.
|
|
*
|
|
* Read into the page cache. If a page already exists, and PageUptodate() is
|
|
* not set, try to fill the page but don't wait for it to become unlocked.
|
|
*
|
|
* If the page does not get brought uptodate, return -EIO.
|
|
*/
|
|
struct page *read_cache_page_async(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *, struct page *),
|
|
void *data)
|
|
{
|
|
return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
|
|
}
|
|
EXPORT_SYMBOL(read_cache_page_async);
|
|
|
|
static struct page *wait_on_page_read(struct page *page)
|
|
{
|
|
if (!IS_ERR(page)) {
|
|
wait_on_page_locked(page);
|
|
if (!PageUptodate(page)) {
|
|
page_cache_release(page);
|
|
page = ERR_PTR(-EIO);
|
|
}
|
|
}
|
|
return page;
|
|
}
|
|
|
|
/**
|
|
* read_cache_page_gfp - read into page cache, using specified page allocation flags.
|
|
* @mapping: the page's address_space
|
|
* @index: the page index
|
|
* @gfp: the page allocator flags to use if allocating
|
|
*
|
|
* This is the same as "read_mapping_page(mapping, index, NULL)", but with
|
|
* any new page allocations done using the specified allocation flags.
|
|
*
|
|
* If the page does not get brought uptodate, return -EIO.
|
|
*/
|
|
struct page *read_cache_page_gfp(struct address_space *mapping,
|
|
pgoff_t index,
|
|
gfp_t gfp)
|
|
{
|
|
filler_t *filler = (filler_t *)mapping->a_ops->readpage;
|
|
|
|
return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp));
|
|
}
|
|
EXPORT_SYMBOL(read_cache_page_gfp);
|
|
|
|
/**
|
|
* read_cache_page - read into page cache, fill it if needed
|
|
* @mapping: the page's address_space
|
|
* @index: the page index
|
|
* @filler: function to perform the read
|
|
* @data: first arg to filler(data, page) function, often left as NULL
|
|
*
|
|
* Read into the page cache. If a page already exists, and PageUptodate() is
|
|
* not set, try to fill the page then wait for it to become unlocked.
|
|
*
|
|
* If the page does not get brought uptodate, return -EIO.
|
|
*/
|
|
struct page *read_cache_page(struct address_space *mapping,
|
|
pgoff_t index,
|
|
int (*filler)(void *, struct page *),
|
|
void *data)
|
|
{
|
|
return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));
|
|
}
|
|
EXPORT_SYMBOL(read_cache_page);
|
|
|
|
static size_t __iovec_copy_from_user_inatomic(char *vaddr,
|
|
const struct iovec *iov, size_t base, size_t bytes)
|
|
{
|
|
size_t copied = 0, left = 0;
|
|
|
|
while (bytes) {
|
|
char __user *buf = iov->iov_base + base;
|
|
int copy = min(bytes, iov->iov_len - base);
|
|
|
|
base = 0;
|
|
left = __copy_from_user_inatomic(vaddr, buf, copy);
|
|
copied += copy;
|
|
bytes -= copy;
|
|
vaddr += copy;
|
|
iov++;
|
|
|
|
if (unlikely(left))
|
|
break;
|
|
}
|
|
return copied - left;
|
|
}
|
|
|
|
/*
|
|
* Copy as much as we can into the page and return the number of bytes which
|
|
* were successfully copied. If a fault is encountered then return the number of
|
|
* bytes which were copied.
|
|
*/
|
|
size_t iov_iter_copy_from_user_atomic(struct page *page,
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
|
{
|
|
char *kaddr;
|
|
size_t copied;
|
|
|
|
BUG_ON(!in_atomic());
|
|
kaddr = kmap_atomic(page);
|
|
if (likely(i->nr_segs == 1)) {
|
|
int left;
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
|
|
copied = bytes - left;
|
|
} else {
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
|
i->iov, i->iov_offset, bytes);
|
|
}
|
|
kunmap_atomic(kaddr);
|
|
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
|
|
|
|
/*
|
|
* This has the same sideeffects and return value as
|
|
* iov_iter_copy_from_user_atomic().
|
|
* The difference is that it attempts to resolve faults.
|
|
* Page must not be locked.
|
|
*/
|
|
size_t iov_iter_copy_from_user(struct page *page,
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
|
{
|
|
char *kaddr;
|
|
size_t copied;
|
|
|
|
kaddr = kmap(page);
|
|
if (likely(i->nr_segs == 1)) {
|
|
int left;
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
left = __copy_from_user(kaddr + offset, buf, bytes);
|
|
copied = bytes - left;
|
|
} else {
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
|
i->iov, i->iov_offset, bytes);
|
|
}
|
|
kunmap(page);
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user);
|
|
|
|
void iov_iter_advance(struct iov_iter *i, size_t bytes)
|
|
{
|
|
BUG_ON(i->count < bytes);
|
|
|
|
if (likely(i->nr_segs == 1)) {
|
|
i->iov_offset += bytes;
|
|
i->count -= bytes;
|
|
} else {
|
|
const struct iovec *iov = i->iov;
|
|
size_t base = i->iov_offset;
|
|
unsigned long nr_segs = i->nr_segs;
|
|
|
|
/*
|
|
* The !iov->iov_len check ensures we skip over unlikely
|
|
* zero-length segments (without overruning the iovec).
|
|
*/
|
|
while (bytes || unlikely(i->count && !iov->iov_len)) {
|
|
int copy;
|
|
|
|
copy = min(bytes, iov->iov_len - base);
|
|
BUG_ON(!i->count || i->count < copy);
|
|
i->count -= copy;
|
|
bytes -= copy;
|
|
base += copy;
|
|
if (iov->iov_len == base) {
|
|
iov++;
|
|
nr_segs--;
|
|
base = 0;
|
|
}
|
|
}
|
|
i->iov = iov;
|
|
i->iov_offset = base;
|
|
i->nr_segs = nr_segs;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_advance);
|
|
|
|
/*
|
|
* Fault in the first iovec of the given iov_iter, to a maximum length
|
|
* of bytes. Returns 0 on success, or non-zero if the memory could not be
|
|
* accessed (ie. because it is an invalid address).
|
|
*
|
|
* writev-intensive code may want this to prefault several iovecs -- that
|
|
* would be possible (callers must not rely on the fact that _only_ the
|
|
* first iovec will be faulted with the current implementation).
|
|
*/
|
|
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
|
|
{
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
|
|
return fault_in_pages_readable(buf, bytes);
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_fault_in_readable);
|
|
|
|
/*
|
|
* Return the count of just the current iov_iter segment.
|
|
*/
|
|
size_t iov_iter_single_seg_count(const struct iov_iter *i)
|
|
{
|
|
const struct iovec *iov = i->iov;
|
|
if (i->nr_segs == 1)
|
|
return i->count;
|
|
else
|
|
return min(i->count, iov->iov_len - i->iov_offset);
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_single_seg_count);
|
|
|
|
/*
|
|
* Performs necessary checks before doing a write
|
|
*
|
|
* Can adjust writing position or amount of bytes to write.
|
|
* Returns appropriate error code that caller should return or
|
|
* zero in case that write should be allowed.
|
|
*/
|
|
inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
|
|
{
|
|
struct inode *inode = file->f_mapping->host;
|
|
unsigned long limit = rlimit(RLIMIT_FSIZE);
|
|
|
|
if (unlikely(*pos < 0))
|
|
return -EINVAL;
|
|
|
|
if (!isblk) {
|
|
/* FIXME: this is for backwards compatibility with 2.4 */
|
|
if (file->f_flags & O_APPEND)
|
|
*pos = i_size_read(inode);
|
|
|
|
if (limit != RLIM_INFINITY) {
|
|
if (*pos >= limit) {
|
|
send_sig(SIGXFSZ, current, 0);
|
|
return -EFBIG;
|
|
}
|
|
if (*count > limit - (typeof(limit))*pos) {
|
|
*count = limit - (typeof(limit))*pos;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* LFS rule
|
|
*/
|
|
if (unlikely(*pos + *count > MAX_NON_LFS &&
|
|
!(file->f_flags & O_LARGEFILE))) {
|
|
if (*pos >= MAX_NON_LFS) {
|
|
return -EFBIG;
|
|
}
|
|
if (*count > MAX_NON_LFS - (unsigned long)*pos) {
|
|
*count = MAX_NON_LFS - (unsigned long)*pos;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Are we about to exceed the fs block limit ?
|
|
*
|
|
* If we have written data it becomes a short write. If we have
|
|
* exceeded without writing data we send a signal and return EFBIG.
|
|
* Linus frestrict idea will clean these up nicely..
|
|
*/
|
|
if (likely(!isblk)) {
|
|
if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
|
|
if (*count || *pos > inode->i_sb->s_maxbytes) {
|
|
return -EFBIG;
|
|
}
|
|
/* zero-length writes at ->s_maxbytes are OK */
|
|
}
|
|
|
|
if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
|
|
*count = inode->i_sb->s_maxbytes - *pos;
|
|
} else {
|
|
#ifdef CONFIG_BLOCK
|
|
loff_t isize;
|
|
if (bdev_read_only(I_BDEV(inode)))
|
|
return -EPERM;
|
|
isize = i_size_read(inode);
|
|
if (*pos >= isize) {
|
|
if (*count || *pos > isize)
|
|
return -ENOSPC;
|
|
}
|
|
|
|
if (*pos + *count > isize)
|
|
*count = isize - *pos;
|
|
#else
|
|
return -EPERM;
|
|
#endif
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(generic_write_checks);
|
|
|
|
int pagecache_write_begin(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned flags,
|
|
struct page **pagep, void **fsdata)
|
|
{
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
|
|
return aops->write_begin(file, mapping, pos, len, flags,
|
|
pagep, fsdata);
|
|
}
|
|
EXPORT_SYMBOL(pagecache_write_begin);
|
|
|
|
int pagecache_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
|
|
mark_page_accessed(page);
|
|
return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
|
|
}
|
|
EXPORT_SYMBOL(pagecache_write_end);
|
|
|
|
ssize_t
|
|
generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long *nr_segs, loff_t pos, loff_t *ppos,
|
|
size_t count, size_t ocount)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
ssize_t written;
|
|
size_t write_len;
|
|
pgoff_t end;
|
|
|
|
if (count != ocount)
|
|
*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
|
|
|
|
write_len = iov_length(iov, *nr_segs);
|
|
end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
|
|
|
|
written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
|
|
if (written)
|
|
goto out;
|
|
|
|
/*
|
|
* After a write we want buffered reads to be sure to go to disk to get
|
|
* the new data. We invalidate clean cached page from the region we're
|
|
* about to write. We do this *before* the write so that we can return
|
|
* without clobbering -EIOCBQUEUED from ->direct_IO().
|
|
*/
|
|
if (mapping->nrpages) {
|
|
written = invalidate_inode_pages2_range(mapping,
|
|
pos >> PAGE_CACHE_SHIFT, end);
|
|
/*
|
|
* If a page can not be invalidated, return 0 to fall back
|
|
* to buffered write.
|
|
*/
|
|
if (written) {
|
|
if (written == -EBUSY)
|
|
return 0;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
|
|
|
|
/*
|
|
* Finally, try again to invalidate clean pages which might have been
|
|
* cached by non-direct readahead, or faulted in by get_user_pages()
|
|
* if the source of the write was an mmap'ed region of the file
|
|
* we're writing. Either one is a pretty crazy thing to do,
|
|
* so we don't support it 100%. If this invalidation
|
|
* fails, tough, the write still worked...
|
|
*/
|
|
if (mapping->nrpages) {
|
|
invalidate_inode_pages2_range(mapping,
|
|
pos >> PAGE_CACHE_SHIFT, end);
|
|
}
|
|
|
|
if (written > 0) {
|
|
pos += written;
|
|
if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
|
|
i_size_write(inode, pos);
|
|
mark_inode_dirty(inode);
|
|
}
|
|
*ppos = pos;
|
|
}
|
|
out:
|
|
return written;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_direct_write);
|
|
|
|
/*
|
|
* Find or create a page at the given pagecache position. Return the locked
|
|
* page. This function is specifically for buffered writes.
|
|
*/
|
|
struct page *grab_cache_page_write_begin(struct address_space *mapping,
|
|
pgoff_t index, unsigned flags)
|
|
{
|
|
int status;
|
|
gfp_t gfp_mask;
|
|
struct page *page;
|
|
gfp_t gfp_notmask = 0;
|
|
|
|
gfp_mask = mapping_gfp_mask(mapping);
|
|
if (mapping_cap_account_dirty(mapping))
|
|
gfp_mask |= __GFP_WRITE;
|
|
if (flags & AOP_FLAG_NOFS)
|
|
gfp_notmask = __GFP_FS;
|
|
repeat:
|
|
page = find_lock_page(mapping, index);
|
|
if (page)
|
|
goto found;
|
|
|
|
page = __page_cache_alloc(gfp_mask & ~gfp_notmask);
|
|
if (!page)
|
|
return NULL;
|
|
status = add_to_page_cache_lru(page, mapping, index,
|
|
GFP_KERNEL & ~gfp_notmask);
|
|
if (unlikely(status)) {
|
|
page_cache_release(page);
|
|
if (status == -EEXIST)
|
|
goto repeat;
|
|
return NULL;
|
|
}
|
|
found:
|
|
wait_for_stable_page(page);
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL(grab_cache_page_write_begin);
|
|
|
|
static ssize_t generic_perform_write(struct file *file,
|
|
struct iov_iter *i, loff_t pos)
|
|
{
|
|
struct address_space *mapping = file->f_mapping;
|
|
const struct address_space_operations *a_ops = mapping->a_ops;
|
|
long status = 0;
|
|
ssize_t written = 0;
|
|
unsigned int flags = 0;
|
|
|
|
/*
|
|
* Copies from kernel address space cannot fail (NFSD is a big user).
|
|
*/
|
|
if (segment_eq(get_fs(), KERNEL_DS))
|
|
flags |= AOP_FLAG_UNINTERRUPTIBLE;
|
|
|
|
do {
|
|
struct page *page;
|
|
unsigned long offset; /* Offset into pagecache page */
|
|
unsigned long bytes; /* Bytes to write to page */
|
|
size_t copied; /* Bytes copied from user */
|
|
void *fsdata;
|
|
|
|
offset = (pos & (PAGE_CACHE_SIZE - 1));
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
|
iov_iter_count(i));
|
|
|
|
again:
|
|
/*
|
|
* Bring in the user page that we will copy from _first_.
|
|
* Otherwise there's a nasty deadlock on copying from the
|
|
* same page as we're writing to, without it being marked
|
|
* up-to-date.
|
|
*
|
|
* Not only is this an optimisation, but it is also required
|
|
* to check that the address is actually valid, when atomic
|
|
* usercopies are used, below.
|
|
*/
|
|
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
|
|
status = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
status = a_ops->write_begin(file, mapping, pos, bytes, flags,
|
|
&page, &fsdata);
|
|
if (unlikely(status))
|
|
break;
|
|
|
|
if (mapping_writably_mapped(mapping))
|
|
flush_dcache_page(page);
|
|
|
|
pagefault_disable();
|
|
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
|
|
pagefault_enable();
|
|
flush_dcache_page(page);
|
|
|
|
mark_page_accessed(page);
|
|
status = a_ops->write_end(file, mapping, pos, bytes, copied,
|
|
page, fsdata);
|
|
if (unlikely(status < 0))
|
|
break;
|
|
copied = status;
|
|
|
|
cond_resched();
|
|
|
|
iov_iter_advance(i, copied);
|
|
if (unlikely(copied == 0)) {
|
|
/*
|
|
* If we were unable to copy any data at all, we must
|
|
* fall back to a single segment length write.
|
|
*
|
|
* If we didn't fallback here, we could livelock
|
|
* because not all segments in the iov can be copied at
|
|
* once without a pagefault.
|
|
*/
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
|
iov_iter_single_seg_count(i));
|
|
goto again;
|
|
}
|
|
pos += copied;
|
|
written += copied;
|
|
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
if (fatal_signal_pending(current)) {
|
|
status = -EINTR;
|
|
break;
|
|
}
|
|
} while (iov_iter_count(i));
|
|
|
|
return written ? written : status;
|
|
}
|
|
|
|
ssize_t
|
|
generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos, loff_t *ppos,
|
|
size_t count, ssize_t written)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
ssize_t status;
|
|
struct iov_iter i;
|
|
|
|
iov_iter_init(&i, iov, nr_segs, count, written);
|
|
status = generic_perform_write(file, &i, pos);
|
|
|
|
if (likely(status >= 0)) {
|
|
written += status;
|
|
*ppos = pos + status;
|
|
}
|
|
|
|
return written ? written : status;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_buffered_write);
|
|
|
|
/**
|
|
* __generic_file_aio_write - write data to a file
|
|
* @iocb: IO state structure (file, offset, etc.)
|
|
* @iov: vector with data to write
|
|
* @nr_segs: number of segments in the vector
|
|
* @ppos: position where to write
|
|
*
|
|
* This function does all the work needed for actually writing data to a
|
|
* file. It does all basic checks, removes SUID from the file, updates
|
|
* modification times and calls proper subroutines depending on whether we
|
|
* do direct IO or a standard buffered write.
|
|
*
|
|
* It expects i_mutex to be grabbed unless we work on a block device or similar
|
|
* object which does not need locking at all.
|
|
*
|
|
* This function does *not* take care of syncing data in case of O_SYNC write.
|
|
* A caller has to handle it. This is mainly due to the fact that we want to
|
|
* avoid syncing under i_mutex.
|
|
*/
|
|
ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t *ppos)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space * mapping = file->f_mapping;
|
|
size_t ocount; /* original count */
|
|
size_t count; /* after file limit checks */
|
|
struct inode *inode = mapping->host;
|
|
loff_t pos;
|
|
ssize_t written;
|
|
ssize_t err;
|
|
|
|
ocount = 0;
|
|
err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
|
|
if (err)
|
|
return err;
|
|
|
|
count = ocount;
|
|
pos = *ppos;
|
|
|
|
/* We can write back this queue in page reclaim */
|
|
current->backing_dev_info = mapping->backing_dev_info;
|
|
written = 0;
|
|
|
|
err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
|
|
if (err)
|
|
goto out;
|
|
|
|
if (count == 0)
|
|
goto out;
|
|
|
|
err = file_remove_suid(file);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = file_update_time(file);
|
|
if (err)
|
|
goto out;
|
|
|
|
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
|
|
if (unlikely(file->f_flags & O_DIRECT)) {
|
|
loff_t endbyte;
|
|
ssize_t written_buffered;
|
|
|
|
written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
|
|
ppos, count, ocount);
|
|
if (written < 0 || written == count)
|
|
goto out;
|
|
/*
|
|
* direct-io write to a hole: fall through to buffered I/O
|
|
* for completing the rest of the request.
|
|
*/
|
|
pos += written;
|
|
count -= written;
|
|
written_buffered = generic_file_buffered_write(iocb, iov,
|
|
nr_segs, pos, ppos, count,
|
|
written);
|
|
/*
|
|
* If generic_file_buffered_write() retuned a synchronous error
|
|
* then we want to return the number of bytes which were
|
|
* direct-written, or the error code if that was zero. Note
|
|
* that this differs from normal direct-io semantics, which
|
|
* will return -EFOO even if some bytes were written.
|
|
*/
|
|
if (written_buffered < 0) {
|
|
err = written_buffered;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* We need to ensure that the page cache pages are written to
|
|
* disk and invalidated to preserve the expected O_DIRECT
|
|
* semantics.
|
|
*/
|
|
endbyte = pos + written_buffered - written - 1;
|
|
err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
|
|
if (err == 0) {
|
|
written = written_buffered;
|
|
invalidate_mapping_pages(mapping,
|
|
pos >> PAGE_CACHE_SHIFT,
|
|
endbyte >> PAGE_CACHE_SHIFT);
|
|
} else {
|
|
/*
|
|
* We don't know how much we wrote, so just return
|
|
* the number of bytes which were direct-written
|
|
*/
|
|
}
|
|
} else {
|
|
written = generic_file_buffered_write(iocb, iov, nr_segs,
|
|
pos, ppos, count, written);
|
|
}
|
|
out:
|
|
current->backing_dev_info = NULL;
|
|
return written ? written : err;
|
|
}
|
|
EXPORT_SYMBOL(__generic_file_aio_write);
|
|
|
|
/**
|
|
* generic_file_aio_write - write data to a file
|
|
* @iocb: IO state structure
|
|
* @iov: vector with data to write
|
|
* @nr_segs: number of segments in the vector
|
|
* @pos: position in file where to write
|
|
*
|
|
* This is a wrapper around __generic_file_aio_write() to be used by most
|
|
* filesystems. It takes care of syncing the file in case of O_SYNC file
|
|
* and acquires i_mutex as needed.
|
|
*/
|
|
ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos)
|
|
{
|
|
struct file *file = iocb->ki_filp;
|
|
struct inode *inode = file->f_mapping->host;
|
|
ssize_t ret;
|
|
|
|
BUG_ON(iocb->ki_pos != pos);
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
if (ret > 0 || ret == -EIOCBQUEUED) {
|
|
ssize_t err;
|
|
|
|
err = generic_write_sync(file, pos, ret);
|
|
if (err < 0 && ret > 0)
|
|
ret = err;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_aio_write);
|
|
|
|
/**
|
|
* try_to_release_page() - release old fs-specific metadata on a page
|
|
*
|
|
* @page: the page which the kernel is trying to free
|
|
* @gfp_mask: memory allocation flags (and I/O mode)
|
|
*
|
|
* The address_space is to try to release any data against the page
|
|
* (presumably at page->private). If the release was successful, return `1'.
|
|
* Otherwise return zero.
|
|
*
|
|
* This may also be called if PG_fscache is set on a page, indicating that the
|
|
* page is known to the local caching routines.
|
|
*
|
|
* The @gfp_mask argument specifies whether I/O may be performed to release
|
|
* this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
|
|
*
|
|
*/
|
|
int try_to_release_page(struct page *page, gfp_t gfp_mask)
|
|
{
|
|
struct address_space * const mapping = page->mapping;
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
if (PageWriteback(page))
|
|
return 0;
|
|
|
|
if (mapping && mapping->a_ops->releasepage)
|
|
return mapping->a_ops->releasepage(page, gfp_mask);
|
|
return try_to_free_buffers(page);
|
|
}
|
|
|
|
EXPORT_SYMBOL(try_to_release_page);
|