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![Linus Torvalds](/assets/img/avatar_default.png)
switching from a user process to a kernel thread. - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj Raghav. - zsmalloc performance improvements from Sergey Senozhatsky. - Yue Zhao has found and fixed some data race issues around the alteration of memcg userspace tunables. - VFS rationalizations from Christoph Hellwig: - removal of most of the callers of write_one_page(). - make __filemap_get_folio()'s return value more useful - Luis Chamberlain has changed tmpfs so it no longer requires swap backing. Use `mount -o noswap'. - Qi Zheng has made the slab shrinkers operate locklessly, providing some scalability benefits. - Keith Busch has improved dmapool's performance, making part of its operations O(1) rather than O(n). - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd, permitting userspace to wr-protect anon memory unpopulated ptes. - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive rather than exclusive, and has fixed a bunch of errors which were caused by its unintuitive meaning. - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature, which causes minor faults to install a write-protected pte. - Vlastimil Babka has done some maintenance work on vma_merge(): cleanups to the kernel code and improvements to our userspace test harness. - Cleanups to do_fault_around() by Lorenzo Stoakes. - Mike Rapoport has moved a lot of initialization code out of various mm/ files and into mm/mm_init.c. - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for DRM, but DRM doesn't use it any more. - Lorenzo has also coverted read_kcore() and vread() to use iterators and has thereby removed the use of bounce buffers in some cases. - Lorenzo has also contributed further cleanups of vma_merge(). - Chaitanya Prakash provides some fixes to the mmap selftesting code. - Matthew Wilcox changes xfs and afs so they no longer take sleeping locks in ->map_page(), a step towards RCUification of pagefaults. - Suren Baghdasaryan has improved mmap_lock scalability by switching to per-VMA locking. - Frederic Weisbecker has reworked the percpu cache draining so that it no longer causes latency glitches on cpu isolated workloads. - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig logic. - Liu Shixin has changed zswap's initialization so we no longer waste a chunk of memory if zswap is not being used. - Yosry Ahmed has improved the performance of memcg statistics flushing. - David Stevens has fixed several issues involving khugepaged, userfaultfd and shmem. - Christoph Hellwig has provided some cleanup work to zram's IO-related code paths. - David Hildenbrand has fixed up some issues in the selftest code's testing of our pte state changing. - Pankaj Raghav has made page_endio() unneeded and has removed it. - Peter Xu contributed some rationalizations of the userfaultfd selftests. - Yosry Ahmed has fixed an issue around memcg's page recalim accounting. - Chaitanya Prakash has fixed some arm-related issues in the selftests/mm code. - Longlong Xia has improved the way in which KSM handles hwpoisoned pages. - Peter Xu fixes a few issues with uffd-wp at fork() time. - Stefan Roesch has changed KSM so that it may now be used on a per-process and per-cgroup basis. -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCZEr3zQAKCRDdBJ7gKXxA jlLoAP0fpQBipwFxED0Us4SKQfupV6z4caXNJGPeay7Aj11/kQD/aMRC2uPfgr96 eMG3kwn2pqkB9ST2QpkaRbxA//eMbQY= =J+Dj -----END PGP SIGNATURE----- Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of switching from a user process to a kernel thread. - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj Raghav. - zsmalloc performance improvements from Sergey Senozhatsky. - Yue Zhao has found and fixed some data race issues around the alteration of memcg userspace tunables. - VFS rationalizations from Christoph Hellwig: - removal of most of the callers of write_one_page() - make __filemap_get_folio()'s return value more useful - Luis Chamberlain has changed tmpfs so it no longer requires swap backing. Use `mount -o noswap'. - Qi Zheng has made the slab shrinkers operate locklessly, providing some scalability benefits. - Keith Busch has improved dmapool's performance, making part of its operations O(1) rather than O(n). - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd, permitting userspace to wr-protect anon memory unpopulated ptes. - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive rather than exclusive, and has fixed a bunch of errors which were caused by its unintuitive meaning. - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature, which causes minor faults to install a write-protected pte. - Vlastimil Babka has done some maintenance work on vma_merge(): cleanups to the kernel code and improvements to our userspace test harness. - Cleanups to do_fault_around() by Lorenzo Stoakes. - Mike Rapoport has moved a lot of initialization code out of various mm/ files and into mm/mm_init.c. - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for DRM, but DRM doesn't use it any more. - Lorenzo has also coverted read_kcore() and vread() to use iterators and has thereby removed the use of bounce buffers in some cases. - Lorenzo has also contributed further cleanups of vma_merge(). - Chaitanya Prakash provides some fixes to the mmap selftesting code. - Matthew Wilcox changes xfs and afs so they no longer take sleeping locks in ->map_page(), a step towards RCUification of pagefaults. - Suren Baghdasaryan has improved mmap_lock scalability by switching to per-VMA locking. - Frederic Weisbecker has reworked the percpu cache draining so that it no longer causes latency glitches on cpu isolated workloads. - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig logic. - Liu Shixin has changed zswap's initialization so we no longer waste a chunk of memory if zswap is not being used. - Yosry Ahmed has improved the performance of memcg statistics flushing. - David Stevens has fixed several issues involving khugepaged, userfaultfd and shmem. - Christoph Hellwig has provided some cleanup work to zram's IO-related code paths. - David Hildenbrand has fixed up some issues in the selftest code's testing of our pte state changing. - Pankaj Raghav has made page_endio() unneeded and has removed it. - Peter Xu contributed some rationalizations of the userfaultfd selftests. - Yosry Ahmed has fixed an issue around memcg's page recalim accounting. - Chaitanya Prakash has fixed some arm-related issues in the selftests/mm code. - Longlong Xia has improved the way in which KSM handles hwpoisoned pages. - Peter Xu fixes a few issues with uffd-wp at fork() time. - Stefan Roesch has changed KSM so that it may now be used on a per-process and per-cgroup basis. * tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits) mm,unmap: avoid flushing TLB in batch if PTE is inaccessible shmem: restrict noswap option to initial user namespace mm/khugepaged: fix conflicting mods to collapse_file() sparse: remove unnecessary 0 values from rc mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area() hugetlb: pte_alloc_huge() to replace huge pte_alloc_map() maple_tree: fix allocation in mas_sparse_area() mm: do not increment pgfault stats when page fault handler retries zsmalloc: allow only one active pool compaction context selftests/mm: add new selftests for KSM mm: add new KSM process and sysfs knobs mm: add new api to enable ksm per process mm: shrinkers: fix debugfs file permissions mm: don't check VMA write permissions if the PTE/PMD indicates write permissions migrate_pages_batch: fix statistics for longterm pin retry userfaultfd: use helper function range_in_vma() lib/show_mem.c: use for_each_populated_zone() simplify code mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list() fs/buffer: convert create_page_buffers to folio_create_buffers fs/buffer: add folio_create_empty_buffers helper ...
1826 lines
53 KiB
C
1826 lines
53 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2010 Red Hat, Inc.
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* Copyright (C) 2016-2019 Christoph Hellwig.
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*/
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#include <linux/module.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/iomap.h>
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#include <linux/pagemap.h>
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#include <linux/uio.h>
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#include <linux/buffer_head.h>
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#include <linux/dax.h>
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#include <linux/writeback.h>
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#include <linux/list_sort.h>
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#include <linux/swap.h>
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#include <linux/bio.h>
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#include <linux/sched/signal.h>
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#include <linux/migrate.h>
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#include "trace.h"
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#include "../internal.h"
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#define IOEND_BATCH_SIZE 4096
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/*
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* Structure allocated for each folio when block size < folio size
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* to track sub-folio uptodate status and I/O completions.
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*/
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struct iomap_page {
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atomic_t read_bytes_pending;
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atomic_t write_bytes_pending;
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spinlock_t uptodate_lock;
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unsigned long uptodate[];
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};
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static inline struct iomap_page *to_iomap_page(struct folio *folio)
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{
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if (folio_test_private(folio))
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return folio_get_private(folio);
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return NULL;
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}
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static struct bio_set iomap_ioend_bioset;
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static struct iomap_page *
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iomap_page_create(struct inode *inode, struct folio *folio, unsigned int flags)
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{
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struct iomap_page *iop = to_iomap_page(folio);
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unsigned int nr_blocks = i_blocks_per_folio(inode, folio);
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gfp_t gfp;
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if (iop || nr_blocks <= 1)
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return iop;
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if (flags & IOMAP_NOWAIT)
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gfp = GFP_NOWAIT;
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else
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gfp = GFP_NOFS | __GFP_NOFAIL;
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iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
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gfp);
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if (iop) {
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spin_lock_init(&iop->uptodate_lock);
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if (folio_test_uptodate(folio))
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bitmap_fill(iop->uptodate, nr_blocks);
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folio_attach_private(folio, iop);
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}
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return iop;
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}
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static void iomap_page_release(struct folio *folio)
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{
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struct iomap_page *iop = folio_detach_private(folio);
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struct inode *inode = folio->mapping->host;
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unsigned int nr_blocks = i_blocks_per_folio(inode, folio);
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if (!iop)
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return;
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WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending));
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WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending));
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WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) !=
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folio_test_uptodate(folio));
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kfree(iop);
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}
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/*
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* Calculate the range inside the folio that we actually need to read.
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*/
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static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
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loff_t *pos, loff_t length, size_t *offp, size_t *lenp)
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{
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struct iomap_page *iop = to_iomap_page(folio);
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loff_t orig_pos = *pos;
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loff_t isize = i_size_read(inode);
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unsigned block_bits = inode->i_blkbits;
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unsigned block_size = (1 << block_bits);
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size_t poff = offset_in_folio(folio, *pos);
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size_t plen = min_t(loff_t, folio_size(folio) - poff, length);
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unsigned first = poff >> block_bits;
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unsigned last = (poff + plen - 1) >> block_bits;
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/*
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* If the block size is smaller than the page size, we need to check the
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* per-block uptodate status and adjust the offset and length if needed
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* to avoid reading in already uptodate ranges.
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*/
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if (iop) {
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unsigned int i;
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/* move forward for each leading block marked uptodate */
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for (i = first; i <= last; i++) {
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if (!test_bit(i, iop->uptodate))
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break;
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*pos += block_size;
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poff += block_size;
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plen -= block_size;
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first++;
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}
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/* truncate len if we find any trailing uptodate block(s) */
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for ( ; i <= last; i++) {
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if (test_bit(i, iop->uptodate)) {
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plen -= (last - i + 1) * block_size;
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last = i - 1;
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break;
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}
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}
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}
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/*
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* If the extent spans the block that contains the i_size, we need to
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* handle both halves separately so that we properly zero data in the
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* page cache for blocks that are entirely outside of i_size.
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*/
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if (orig_pos <= isize && orig_pos + length > isize) {
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unsigned end = offset_in_folio(folio, isize - 1) >> block_bits;
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if (first <= end && last > end)
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plen -= (last - end) * block_size;
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}
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*offp = poff;
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*lenp = plen;
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}
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static void iomap_iop_set_range_uptodate(struct folio *folio,
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struct iomap_page *iop, size_t off, size_t len)
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{
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struct inode *inode = folio->mapping->host;
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unsigned first = off >> inode->i_blkbits;
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unsigned last = (off + len - 1) >> inode->i_blkbits;
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unsigned long flags;
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spin_lock_irqsave(&iop->uptodate_lock, flags);
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bitmap_set(iop->uptodate, first, last - first + 1);
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if (bitmap_full(iop->uptodate, i_blocks_per_folio(inode, folio)))
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folio_mark_uptodate(folio);
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spin_unlock_irqrestore(&iop->uptodate_lock, flags);
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}
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static void iomap_set_range_uptodate(struct folio *folio,
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struct iomap_page *iop, size_t off, size_t len)
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{
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if (iop)
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iomap_iop_set_range_uptodate(folio, iop, off, len);
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else
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folio_mark_uptodate(folio);
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}
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static void iomap_finish_folio_read(struct folio *folio, size_t offset,
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size_t len, int error)
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{
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struct iomap_page *iop = to_iomap_page(folio);
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if (unlikely(error)) {
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folio_clear_uptodate(folio);
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folio_set_error(folio);
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} else {
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iomap_set_range_uptodate(folio, iop, offset, len);
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}
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if (!iop || atomic_sub_and_test(len, &iop->read_bytes_pending))
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folio_unlock(folio);
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}
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static void iomap_read_end_io(struct bio *bio)
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{
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int error = blk_status_to_errno(bio->bi_status);
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struct folio_iter fi;
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bio_for_each_folio_all(fi, bio)
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iomap_finish_folio_read(fi.folio, fi.offset, fi.length, error);
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bio_put(bio);
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}
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struct iomap_readpage_ctx {
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struct folio *cur_folio;
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bool cur_folio_in_bio;
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struct bio *bio;
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struct readahead_control *rac;
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};
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/**
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* iomap_read_inline_data - copy inline data into the page cache
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* @iter: iteration structure
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* @folio: folio to copy to
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*
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* Copy the inline data in @iter into @folio and zero out the rest of the folio.
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* Only a single IOMAP_INLINE extent is allowed at the end of each file.
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* Returns zero for success to complete the read, or the usual negative errno.
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*/
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static int iomap_read_inline_data(const struct iomap_iter *iter,
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struct folio *folio)
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{
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struct iomap_page *iop;
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const struct iomap *iomap = iomap_iter_srcmap(iter);
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size_t size = i_size_read(iter->inode) - iomap->offset;
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size_t poff = offset_in_page(iomap->offset);
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size_t offset = offset_in_folio(folio, iomap->offset);
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void *addr;
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if (folio_test_uptodate(folio))
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return 0;
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if (WARN_ON_ONCE(size > PAGE_SIZE - poff))
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return -EIO;
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if (WARN_ON_ONCE(size > PAGE_SIZE -
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offset_in_page(iomap->inline_data)))
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return -EIO;
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if (WARN_ON_ONCE(size > iomap->length))
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return -EIO;
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if (offset > 0)
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iop = iomap_page_create(iter->inode, folio, iter->flags);
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else
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iop = to_iomap_page(folio);
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addr = kmap_local_folio(folio, offset);
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memcpy(addr, iomap->inline_data, size);
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memset(addr + size, 0, PAGE_SIZE - poff - size);
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kunmap_local(addr);
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iomap_set_range_uptodate(folio, iop, offset, PAGE_SIZE - poff);
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return 0;
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}
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static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
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loff_t pos)
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{
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const struct iomap *srcmap = iomap_iter_srcmap(iter);
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return srcmap->type != IOMAP_MAPPED ||
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(srcmap->flags & IOMAP_F_NEW) ||
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pos >= i_size_read(iter->inode);
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}
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static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
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struct iomap_readpage_ctx *ctx, loff_t offset)
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{
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const struct iomap *iomap = &iter->iomap;
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loff_t pos = iter->pos + offset;
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loff_t length = iomap_length(iter) - offset;
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struct folio *folio = ctx->cur_folio;
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struct iomap_page *iop;
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loff_t orig_pos = pos;
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size_t poff, plen;
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sector_t sector;
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if (iomap->type == IOMAP_INLINE)
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return iomap_read_inline_data(iter, folio);
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/* zero post-eof blocks as the page may be mapped */
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iop = iomap_page_create(iter->inode, folio, iter->flags);
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iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff, &plen);
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if (plen == 0)
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goto done;
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if (iomap_block_needs_zeroing(iter, pos)) {
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folio_zero_range(folio, poff, plen);
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iomap_set_range_uptodate(folio, iop, poff, plen);
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goto done;
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}
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ctx->cur_folio_in_bio = true;
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if (iop)
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atomic_add(plen, &iop->read_bytes_pending);
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sector = iomap_sector(iomap, pos);
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if (!ctx->bio ||
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bio_end_sector(ctx->bio) != sector ||
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!bio_add_folio(ctx->bio, folio, plen, poff)) {
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gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
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gfp_t orig_gfp = gfp;
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unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
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if (ctx->bio)
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submit_bio(ctx->bio);
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if (ctx->rac) /* same as readahead_gfp_mask */
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gfp |= __GFP_NORETRY | __GFP_NOWARN;
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ctx->bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs),
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REQ_OP_READ, gfp);
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/*
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* If the bio_alloc fails, try it again for a single page to
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* avoid having to deal with partial page reads. This emulates
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* what do_mpage_read_folio does.
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*/
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if (!ctx->bio) {
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ctx->bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ,
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orig_gfp);
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}
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if (ctx->rac)
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ctx->bio->bi_opf |= REQ_RAHEAD;
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ctx->bio->bi_iter.bi_sector = sector;
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ctx->bio->bi_end_io = iomap_read_end_io;
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bio_add_folio(ctx->bio, folio, plen, poff);
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}
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done:
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/*
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* Move the caller beyond our range so that it keeps making progress.
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* For that, we have to include any leading non-uptodate ranges, but
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* we can skip trailing ones as they will be handled in the next
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* iteration.
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*/
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return pos - orig_pos + plen;
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}
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int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
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{
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struct iomap_iter iter = {
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.inode = folio->mapping->host,
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.pos = folio_pos(folio),
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.len = folio_size(folio),
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};
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struct iomap_readpage_ctx ctx = {
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.cur_folio = folio,
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};
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int ret;
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trace_iomap_readpage(iter.inode, 1);
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while ((ret = iomap_iter(&iter, ops)) > 0)
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iter.processed = iomap_readpage_iter(&iter, &ctx, 0);
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if (ret < 0)
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folio_set_error(folio);
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if (ctx.bio) {
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|
submit_bio(ctx.bio);
|
|
WARN_ON_ONCE(!ctx.cur_folio_in_bio);
|
|
} else {
|
|
WARN_ON_ONCE(ctx.cur_folio_in_bio);
|
|
folio_unlock(folio);
|
|
}
|
|
|
|
/*
|
|
* Just like mpage_readahead and block_read_full_folio, we always
|
|
* return 0 and just set the folio error flag on errors. This
|
|
* should be cleaned up throughout the stack eventually.
|
|
*/
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_read_folio);
|
|
|
|
static loff_t iomap_readahead_iter(const struct iomap_iter *iter,
|
|
struct iomap_readpage_ctx *ctx)
|
|
{
|
|
loff_t length = iomap_length(iter);
|
|
loff_t done, ret;
|
|
|
|
for (done = 0; done < length; done += ret) {
|
|
if (ctx->cur_folio &&
|
|
offset_in_folio(ctx->cur_folio, iter->pos + done) == 0) {
|
|
if (!ctx->cur_folio_in_bio)
|
|
folio_unlock(ctx->cur_folio);
|
|
ctx->cur_folio = NULL;
|
|
}
|
|
if (!ctx->cur_folio) {
|
|
ctx->cur_folio = readahead_folio(ctx->rac);
|
|
ctx->cur_folio_in_bio = false;
|
|
}
|
|
ret = iomap_readpage_iter(iter, ctx, done);
|
|
if (ret <= 0)
|
|
return ret;
|
|
}
|
|
|
|
return done;
|
|
}
|
|
|
|
/**
|
|
* iomap_readahead - Attempt to read pages from a file.
|
|
* @rac: Describes the pages to be read.
|
|
* @ops: The operations vector for the filesystem.
|
|
*
|
|
* This function is for filesystems to call to implement their readahead
|
|
* address_space operation.
|
|
*
|
|
* Context: The @ops callbacks may submit I/O (eg to read the addresses of
|
|
* blocks from disc), and may wait for it. The caller may be trying to
|
|
* access a different page, and so sleeping excessively should be avoided.
|
|
* It may allocate memory, but should avoid costly allocations. This
|
|
* function is called with memalloc_nofs set, so allocations will not cause
|
|
* the filesystem to be reentered.
|
|
*/
|
|
void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
|
|
{
|
|
struct iomap_iter iter = {
|
|
.inode = rac->mapping->host,
|
|
.pos = readahead_pos(rac),
|
|
.len = readahead_length(rac),
|
|
};
|
|
struct iomap_readpage_ctx ctx = {
|
|
.rac = rac,
|
|
};
|
|
|
|
trace_iomap_readahead(rac->mapping->host, readahead_count(rac));
|
|
|
|
while (iomap_iter(&iter, ops) > 0)
|
|
iter.processed = iomap_readahead_iter(&iter, &ctx);
|
|
|
|
if (ctx.bio)
|
|
submit_bio(ctx.bio);
|
|
if (ctx.cur_folio) {
|
|
if (!ctx.cur_folio_in_bio)
|
|
folio_unlock(ctx.cur_folio);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_readahead);
|
|
|
|
/*
|
|
* iomap_is_partially_uptodate checks whether blocks within a folio are
|
|
* uptodate or not.
|
|
*
|
|
* Returns true if all blocks which correspond to the specified part
|
|
* of the folio are uptodate.
|
|
*/
|
|
bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
|
|
{
|
|
struct iomap_page *iop = to_iomap_page(folio);
|
|
struct inode *inode = folio->mapping->host;
|
|
unsigned first, last, i;
|
|
|
|
if (!iop)
|
|
return false;
|
|
|
|
/* Caller's range may extend past the end of this folio */
|
|
count = min(folio_size(folio) - from, count);
|
|
|
|
/* First and last blocks in range within folio */
|
|
first = from >> inode->i_blkbits;
|
|
last = (from + count - 1) >> inode->i_blkbits;
|
|
|
|
for (i = first; i <= last; i++)
|
|
if (!test_bit(i, iop->uptodate))
|
|
return false;
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
|
|
|
|
/**
|
|
* iomap_get_folio - get a folio reference for writing
|
|
* @iter: iteration structure
|
|
* @pos: start offset of write
|
|
*
|
|
* Returns a locked reference to the folio at @pos, or an error pointer if the
|
|
* folio could not be obtained.
|
|
*/
|
|
struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos)
|
|
{
|
|
unsigned fgp = FGP_WRITEBEGIN | FGP_NOFS;
|
|
|
|
if (iter->flags & IOMAP_NOWAIT)
|
|
fgp |= FGP_NOWAIT;
|
|
|
|
return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
|
|
fgp, mapping_gfp_mask(iter->inode->i_mapping));
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_get_folio);
|
|
|
|
bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags)
|
|
{
|
|
trace_iomap_release_folio(folio->mapping->host, folio_pos(folio),
|
|
folio_size(folio));
|
|
|
|
/*
|
|
* mm accommodates an old ext3 case where clean folios might
|
|
* not have had the dirty bit cleared. Thus, it can send actual
|
|
* dirty folios to ->release_folio() via shrink_active_list();
|
|
* skip those here.
|
|
*/
|
|
if (folio_test_dirty(folio) || folio_test_writeback(folio))
|
|
return false;
|
|
iomap_page_release(folio);
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_release_folio);
|
|
|
|
void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len)
|
|
{
|
|
trace_iomap_invalidate_folio(folio->mapping->host,
|
|
folio_pos(folio) + offset, len);
|
|
|
|
/*
|
|
* If we're invalidating the entire folio, clear the dirty state
|
|
* from it and release it to avoid unnecessary buildup of the LRU.
|
|
*/
|
|
if (offset == 0 && len == folio_size(folio)) {
|
|
WARN_ON_ONCE(folio_test_writeback(folio));
|
|
folio_cancel_dirty(folio);
|
|
iomap_page_release(folio);
|
|
} else if (folio_test_large(folio)) {
|
|
/* Must release the iop so the page can be split */
|
|
WARN_ON_ONCE(!folio_test_uptodate(folio) &&
|
|
folio_test_dirty(folio));
|
|
iomap_page_release(folio);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_invalidate_folio);
|
|
|
|
static void
|
|
iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
|
|
{
|
|
loff_t i_size = i_size_read(inode);
|
|
|
|
/*
|
|
* Only truncate newly allocated pages beyoned EOF, even if the
|
|
* write started inside the existing inode size.
|
|
*/
|
|
if (pos + len > i_size)
|
|
truncate_pagecache_range(inode, max(pos, i_size),
|
|
pos + len - 1);
|
|
}
|
|
|
|
static int iomap_read_folio_sync(loff_t block_start, struct folio *folio,
|
|
size_t poff, size_t plen, const struct iomap *iomap)
|
|
{
|
|
struct bio_vec bvec;
|
|
struct bio bio;
|
|
|
|
bio_init(&bio, iomap->bdev, &bvec, 1, REQ_OP_READ);
|
|
bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
|
|
bio_add_folio(&bio, folio, plen, poff);
|
|
return submit_bio_wait(&bio);
|
|
}
|
|
|
|
static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
|
|
size_t len, struct folio *folio)
|
|
{
|
|
const struct iomap *srcmap = iomap_iter_srcmap(iter);
|
|
struct iomap_page *iop;
|
|
loff_t block_size = i_blocksize(iter->inode);
|
|
loff_t block_start = round_down(pos, block_size);
|
|
loff_t block_end = round_up(pos + len, block_size);
|
|
unsigned int nr_blocks = i_blocks_per_folio(iter->inode, folio);
|
|
size_t from = offset_in_folio(folio, pos), to = from + len;
|
|
size_t poff, plen;
|
|
|
|
if (folio_test_uptodate(folio))
|
|
return 0;
|
|
folio_clear_error(folio);
|
|
|
|
iop = iomap_page_create(iter->inode, folio, iter->flags);
|
|
if ((iter->flags & IOMAP_NOWAIT) && !iop && nr_blocks > 1)
|
|
return -EAGAIN;
|
|
|
|
do {
|
|
iomap_adjust_read_range(iter->inode, folio, &block_start,
|
|
block_end - block_start, &poff, &plen);
|
|
if (plen == 0)
|
|
break;
|
|
|
|
if (!(iter->flags & IOMAP_UNSHARE) &&
|
|
(from <= poff || from >= poff + plen) &&
|
|
(to <= poff || to >= poff + plen))
|
|
continue;
|
|
|
|
if (iomap_block_needs_zeroing(iter, block_start)) {
|
|
if (WARN_ON_ONCE(iter->flags & IOMAP_UNSHARE))
|
|
return -EIO;
|
|
folio_zero_segments(folio, poff, from, to, poff + plen);
|
|
} else {
|
|
int status;
|
|
|
|
if (iter->flags & IOMAP_NOWAIT)
|
|
return -EAGAIN;
|
|
|
|
status = iomap_read_folio_sync(block_start, folio,
|
|
poff, plen, srcmap);
|
|
if (status)
|
|
return status;
|
|
}
|
|
iomap_set_range_uptodate(folio, iop, poff, plen);
|
|
} while ((block_start += plen) < block_end);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct folio *__iomap_get_folio(struct iomap_iter *iter, loff_t pos,
|
|
size_t len)
|
|
{
|
|
const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
|
|
|
|
if (folio_ops && folio_ops->get_folio)
|
|
return folio_ops->get_folio(iter, pos, len);
|
|
else
|
|
return iomap_get_folio(iter, pos);
|
|
}
|
|
|
|
static void __iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret,
|
|
struct folio *folio)
|
|
{
|
|
const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
|
|
|
|
if (folio_ops && folio_ops->put_folio) {
|
|
folio_ops->put_folio(iter->inode, pos, ret, folio);
|
|
} else {
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
}
|
|
}
|
|
|
|
static int iomap_write_begin_inline(const struct iomap_iter *iter,
|
|
struct folio *folio)
|
|
{
|
|
/* needs more work for the tailpacking case; disable for now */
|
|
if (WARN_ON_ONCE(iomap_iter_srcmap(iter)->offset != 0))
|
|
return -EIO;
|
|
return iomap_read_inline_data(iter, folio);
|
|
}
|
|
|
|
static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
|
|
size_t len, struct folio **foliop)
|
|
{
|
|
const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
|
|
const struct iomap *srcmap = iomap_iter_srcmap(iter);
|
|
struct folio *folio;
|
|
int status = 0;
|
|
|
|
BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
|
|
if (srcmap != &iter->iomap)
|
|
BUG_ON(pos + len > srcmap->offset + srcmap->length);
|
|
|
|
if (fatal_signal_pending(current))
|
|
return -EINTR;
|
|
|
|
if (!mapping_large_folio_support(iter->inode->i_mapping))
|
|
len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
|
|
|
|
folio = __iomap_get_folio(iter, pos, len);
|
|
if (IS_ERR(folio))
|
|
return PTR_ERR(folio);
|
|
|
|
/*
|
|
* Now we have a locked folio, before we do anything with it we need to
|
|
* check that the iomap we have cached is not stale. The inode extent
|
|
* mapping can change due to concurrent IO in flight (e.g.
|
|
* IOMAP_UNWRITTEN state can change and memory reclaim could have
|
|
* reclaimed a previously partially written page at this index after IO
|
|
* completion before this write reaches this file offset) and hence we
|
|
* could do the wrong thing here (zero a page range incorrectly or fail
|
|
* to zero) and corrupt data.
|
|
*/
|
|
if (folio_ops && folio_ops->iomap_valid) {
|
|
bool iomap_valid = folio_ops->iomap_valid(iter->inode,
|
|
&iter->iomap);
|
|
if (!iomap_valid) {
|
|
iter->iomap.flags |= IOMAP_F_STALE;
|
|
status = 0;
|
|
goto out_unlock;
|
|
}
|
|
}
|
|
|
|
if (pos + len > folio_pos(folio) + folio_size(folio))
|
|
len = folio_pos(folio) + folio_size(folio) - pos;
|
|
|
|
if (srcmap->type == IOMAP_INLINE)
|
|
status = iomap_write_begin_inline(iter, folio);
|
|
else if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
|
|
status = __block_write_begin_int(folio, pos, len, NULL, srcmap);
|
|
else
|
|
status = __iomap_write_begin(iter, pos, len, folio);
|
|
|
|
if (unlikely(status))
|
|
goto out_unlock;
|
|
|
|
*foliop = folio;
|
|
return 0;
|
|
|
|
out_unlock:
|
|
__iomap_put_folio(iter, pos, 0, folio);
|
|
iomap_write_failed(iter->inode, pos, len);
|
|
|
|
return status;
|
|
}
|
|
|
|
static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
|
|
size_t copied, struct folio *folio)
|
|
{
|
|
struct iomap_page *iop = to_iomap_page(folio);
|
|
flush_dcache_folio(folio);
|
|
|
|
/*
|
|
* The blocks that were entirely written will now be uptodate, so we
|
|
* don't have to worry about a read_folio reading them and overwriting a
|
|
* partial write. However, if we've encountered a short write and only
|
|
* partially written into a block, it will not be marked uptodate, so a
|
|
* read_folio might come in and destroy our partial write.
|
|
*
|
|
* Do the simplest thing and just treat any short write to a
|
|
* non-uptodate page as a zero-length write, and force the caller to
|
|
* redo the whole thing.
|
|
*/
|
|
if (unlikely(copied < len && !folio_test_uptodate(folio)))
|
|
return 0;
|
|
iomap_set_range_uptodate(folio, iop, offset_in_folio(folio, pos), len);
|
|
filemap_dirty_folio(inode->i_mapping, folio);
|
|
return copied;
|
|
}
|
|
|
|
static size_t iomap_write_end_inline(const struct iomap_iter *iter,
|
|
struct folio *folio, loff_t pos, size_t copied)
|
|
{
|
|
const struct iomap *iomap = &iter->iomap;
|
|
void *addr;
|
|
|
|
WARN_ON_ONCE(!folio_test_uptodate(folio));
|
|
BUG_ON(!iomap_inline_data_valid(iomap));
|
|
|
|
flush_dcache_folio(folio);
|
|
addr = kmap_local_folio(folio, pos);
|
|
memcpy(iomap_inline_data(iomap, pos), addr, copied);
|
|
kunmap_local(addr);
|
|
|
|
mark_inode_dirty(iter->inode);
|
|
return copied;
|
|
}
|
|
|
|
/* Returns the number of bytes copied. May be 0. Cannot be an errno. */
|
|
static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
|
|
size_t copied, struct folio *folio)
|
|
{
|
|
const struct iomap *srcmap = iomap_iter_srcmap(iter);
|
|
loff_t old_size = iter->inode->i_size;
|
|
size_t ret;
|
|
|
|
if (srcmap->type == IOMAP_INLINE) {
|
|
ret = iomap_write_end_inline(iter, folio, pos, copied);
|
|
} else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
|
|
ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,
|
|
copied, &folio->page, NULL);
|
|
} else {
|
|
ret = __iomap_write_end(iter->inode, pos, len, copied, folio);
|
|
}
|
|
|
|
/*
|
|
* Update the in-memory inode size after copying the data into the page
|
|
* cache. It's up to the file system to write the updated size to disk,
|
|
* preferably after I/O completion so that no stale data is exposed.
|
|
*/
|
|
if (pos + ret > old_size) {
|
|
i_size_write(iter->inode, pos + ret);
|
|
iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
|
|
}
|
|
__iomap_put_folio(iter, pos, ret, folio);
|
|
|
|
if (old_size < pos)
|
|
pagecache_isize_extended(iter->inode, old_size, pos);
|
|
if (ret < len)
|
|
iomap_write_failed(iter->inode, pos + ret, len - ret);
|
|
return ret;
|
|
}
|
|
|
|
static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
|
|
{
|
|
loff_t length = iomap_length(iter);
|
|
loff_t pos = iter->pos;
|
|
ssize_t written = 0;
|
|
long status = 0;
|
|
struct address_space *mapping = iter->inode->i_mapping;
|
|
unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0;
|
|
|
|
do {
|
|
struct folio *folio;
|
|
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 */
|
|
|
|
offset = offset_in_page(pos);
|
|
bytes = min_t(unsigned long, PAGE_SIZE - offset,
|
|
iov_iter_count(i));
|
|
again:
|
|
status = balance_dirty_pages_ratelimited_flags(mapping,
|
|
bdp_flags);
|
|
if (unlikely(status))
|
|
break;
|
|
|
|
if (bytes > length)
|
|
bytes = length;
|
|
|
|
/*
|
|
* Bring in the user page that we'll 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.
|
|
*
|
|
* For async buffered writes the assumption is that the user
|
|
* page has already been faulted in. This can be optimized by
|
|
* faulting the user page.
|
|
*/
|
|
if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {
|
|
status = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
status = iomap_write_begin(iter, pos, bytes, &folio);
|
|
if (unlikely(status))
|
|
break;
|
|
if (iter->iomap.flags & IOMAP_F_STALE)
|
|
break;
|
|
|
|
page = folio_file_page(folio, pos >> PAGE_SHIFT);
|
|
if (mapping_writably_mapped(mapping))
|
|
flush_dcache_page(page);
|
|
|
|
copied = copy_page_from_iter_atomic(page, offset, bytes, i);
|
|
|
|
status = iomap_write_end(iter, pos, bytes, copied, folio);
|
|
|
|
if (unlikely(copied != status))
|
|
iov_iter_revert(i, copied - status);
|
|
|
|
cond_resched();
|
|
if (unlikely(status == 0)) {
|
|
/*
|
|
* A short copy made iomap_write_end() reject the
|
|
* thing entirely. Might be memory poisoning
|
|
* halfway through, might be a race with munmap,
|
|
* might be severe memory pressure.
|
|
*/
|
|
if (copied)
|
|
bytes = copied;
|
|
goto again;
|
|
}
|
|
pos += status;
|
|
written += status;
|
|
length -= status;
|
|
} while (iov_iter_count(i) && length);
|
|
|
|
if (status == -EAGAIN) {
|
|
iov_iter_revert(i, written);
|
|
return -EAGAIN;
|
|
}
|
|
return written ? written : status;
|
|
}
|
|
|
|
ssize_t
|
|
iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct iomap_iter iter = {
|
|
.inode = iocb->ki_filp->f_mapping->host,
|
|
.pos = iocb->ki_pos,
|
|
.len = iov_iter_count(i),
|
|
.flags = IOMAP_WRITE,
|
|
};
|
|
int ret;
|
|
|
|
if (iocb->ki_flags & IOCB_NOWAIT)
|
|
iter.flags |= IOMAP_NOWAIT;
|
|
|
|
while ((ret = iomap_iter(&iter, ops)) > 0)
|
|
iter.processed = iomap_write_iter(&iter, i);
|
|
if (iter.pos == iocb->ki_pos)
|
|
return ret;
|
|
return iter.pos - iocb->ki_pos;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
|
|
|
|
/*
|
|
* Scan the data range passed to us for dirty page cache folios. If we find a
|
|
* dirty folio, punch out the preceeding range and update the offset from which
|
|
* the next punch will start from.
|
|
*
|
|
* We can punch out storage reservations under clean pages because they either
|
|
* contain data that has been written back - in which case the delalloc punch
|
|
* over that range is a no-op - or they have been read faults in which case they
|
|
* contain zeroes and we can remove the delalloc backing range and any new
|
|
* writes to those pages will do the normal hole filling operation...
|
|
*
|
|
* This makes the logic simple: we only need to keep the delalloc extents only
|
|
* over the dirty ranges of the page cache.
|
|
*
|
|
* This function uses [start_byte, end_byte) intervals (i.e. open ended) to
|
|
* simplify range iterations.
|
|
*/
|
|
static int iomap_write_delalloc_scan(struct inode *inode,
|
|
loff_t *punch_start_byte, loff_t start_byte, loff_t end_byte,
|
|
int (*punch)(struct inode *inode, loff_t offset, loff_t length))
|
|
{
|
|
while (start_byte < end_byte) {
|
|
struct folio *folio;
|
|
|
|
/* grab locked page */
|
|
folio = filemap_lock_folio(inode->i_mapping,
|
|
start_byte >> PAGE_SHIFT);
|
|
if (IS_ERR(folio)) {
|
|
start_byte = ALIGN_DOWN(start_byte, PAGE_SIZE) +
|
|
PAGE_SIZE;
|
|
continue;
|
|
}
|
|
|
|
/* if dirty, punch up to offset */
|
|
if (folio_test_dirty(folio)) {
|
|
if (start_byte > *punch_start_byte) {
|
|
int error;
|
|
|
|
error = punch(inode, *punch_start_byte,
|
|
start_byte - *punch_start_byte);
|
|
if (error) {
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
return error;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Make sure the next punch start is correctly bound to
|
|
* the end of this data range, not the end of the folio.
|
|
*/
|
|
*punch_start_byte = min_t(loff_t, end_byte,
|
|
folio_next_index(folio) << PAGE_SHIFT);
|
|
}
|
|
|
|
/* move offset to start of next folio in range */
|
|
start_byte = folio_next_index(folio) << PAGE_SHIFT;
|
|
folio_unlock(folio);
|
|
folio_put(folio);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Punch out all the delalloc blocks in the range given except for those that
|
|
* have dirty data still pending in the page cache - those are going to be
|
|
* written and so must still retain the delalloc backing for writeback.
|
|
*
|
|
* As we are scanning the page cache for data, we don't need to reimplement the
|
|
* wheel - mapping_seek_hole_data() does exactly what we need to identify the
|
|
* start and end of data ranges correctly even for sub-folio block sizes. This
|
|
* byte range based iteration is especially convenient because it means we
|
|
* don't have to care about variable size folios, nor where the start or end of
|
|
* the data range lies within a folio, if they lie within the same folio or even
|
|
* if there are multiple discontiguous data ranges within the folio.
|
|
*
|
|
* It should be noted that mapping_seek_hole_data() is not aware of EOF, and so
|
|
* can return data ranges that exist in the cache beyond EOF. e.g. a page fault
|
|
* spanning EOF will initialise the post-EOF data to zeroes and mark it up to
|
|
* date. A write page fault can then mark it dirty. If we then fail a write()
|
|
* beyond EOF into that up to date cached range, we allocate a delalloc block
|
|
* beyond EOF and then have to punch it out. Because the range is up to date,
|
|
* mapping_seek_hole_data() will return it, and we will skip the punch because
|
|
* the folio is dirty. THis is incorrect - we always need to punch out delalloc
|
|
* beyond EOF in this case as writeback will never write back and covert that
|
|
* delalloc block beyond EOF. Hence we limit the cached data scan range to EOF,
|
|
* resulting in always punching out the range from the EOF to the end of the
|
|
* range the iomap spans.
|
|
*
|
|
* Intervals are of the form [start_byte, end_byte) (i.e. open ended) because it
|
|
* matches the intervals returned by mapping_seek_hole_data(). i.e. SEEK_DATA
|
|
* returns the start of a data range (start_byte), and SEEK_HOLE(start_byte)
|
|
* returns the end of the data range (data_end). Using closed intervals would
|
|
* require sprinkling this code with magic "+ 1" and "- 1" arithmetic and expose
|
|
* the code to subtle off-by-one bugs....
|
|
*/
|
|
static int iomap_write_delalloc_release(struct inode *inode,
|
|
loff_t start_byte, loff_t end_byte,
|
|
int (*punch)(struct inode *inode, loff_t pos, loff_t length))
|
|
{
|
|
loff_t punch_start_byte = start_byte;
|
|
loff_t scan_end_byte = min(i_size_read(inode), end_byte);
|
|
int error = 0;
|
|
|
|
/*
|
|
* Lock the mapping to avoid races with page faults re-instantiating
|
|
* folios and dirtying them via ->page_mkwrite whilst we walk the
|
|
* cache and perform delalloc extent removal. Failing to do this can
|
|
* leave dirty pages with no space reservation in the cache.
|
|
*/
|
|
filemap_invalidate_lock(inode->i_mapping);
|
|
while (start_byte < scan_end_byte) {
|
|
loff_t data_end;
|
|
|
|
start_byte = mapping_seek_hole_data(inode->i_mapping,
|
|
start_byte, scan_end_byte, SEEK_DATA);
|
|
/*
|
|
* If there is no more data to scan, all that is left is to
|
|
* punch out the remaining range.
|
|
*/
|
|
if (start_byte == -ENXIO || start_byte == scan_end_byte)
|
|
break;
|
|
if (start_byte < 0) {
|
|
error = start_byte;
|
|
goto out_unlock;
|
|
}
|
|
WARN_ON_ONCE(start_byte < punch_start_byte);
|
|
WARN_ON_ONCE(start_byte > scan_end_byte);
|
|
|
|
/*
|
|
* We find the end of this contiguous cached data range by
|
|
* seeking from start_byte to the beginning of the next hole.
|
|
*/
|
|
data_end = mapping_seek_hole_data(inode->i_mapping, start_byte,
|
|
scan_end_byte, SEEK_HOLE);
|
|
if (data_end < 0) {
|
|
error = data_end;
|
|
goto out_unlock;
|
|
}
|
|
WARN_ON_ONCE(data_end <= start_byte);
|
|
WARN_ON_ONCE(data_end > scan_end_byte);
|
|
|
|
error = iomap_write_delalloc_scan(inode, &punch_start_byte,
|
|
start_byte, data_end, punch);
|
|
if (error)
|
|
goto out_unlock;
|
|
|
|
/* The next data search starts at the end of this one. */
|
|
start_byte = data_end;
|
|
}
|
|
|
|
if (punch_start_byte < end_byte)
|
|
error = punch(inode, punch_start_byte,
|
|
end_byte - punch_start_byte);
|
|
out_unlock:
|
|
filemap_invalidate_unlock(inode->i_mapping);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* When a short write occurs, the filesystem may need to remove reserved space
|
|
* that was allocated in ->iomap_begin from it's ->iomap_end method. For
|
|
* filesystems that use delayed allocation, we need to punch out delalloc
|
|
* extents from the range that are not dirty in the page cache. As the write can
|
|
* race with page faults, there can be dirty pages over the delalloc extent
|
|
* outside the range of a short write but still within the delalloc extent
|
|
* allocated for this iomap.
|
|
*
|
|
* This function uses [start_byte, end_byte) intervals (i.e. open ended) to
|
|
* simplify range iterations.
|
|
*
|
|
* The punch() callback *must* only punch delalloc extents in the range passed
|
|
* to it. It must skip over all other types of extents in the range and leave
|
|
* them completely unchanged. It must do this punch atomically with respect to
|
|
* other extent modifications.
|
|
*
|
|
* The punch() callback may be called with a folio locked to prevent writeback
|
|
* extent allocation racing at the edge of the range we are currently punching.
|
|
* The locked folio may or may not cover the range being punched, so it is not
|
|
* safe for the punch() callback to lock folios itself.
|
|
*
|
|
* Lock order is:
|
|
*
|
|
* inode->i_rwsem (shared or exclusive)
|
|
* inode->i_mapping->invalidate_lock (exclusive)
|
|
* folio_lock()
|
|
* ->punch
|
|
* internal filesystem allocation lock
|
|
*/
|
|
int iomap_file_buffered_write_punch_delalloc(struct inode *inode,
|
|
struct iomap *iomap, loff_t pos, loff_t length,
|
|
ssize_t written,
|
|
int (*punch)(struct inode *inode, loff_t pos, loff_t length))
|
|
{
|
|
loff_t start_byte;
|
|
loff_t end_byte;
|
|
int blocksize = i_blocksize(inode);
|
|
|
|
if (iomap->type != IOMAP_DELALLOC)
|
|
return 0;
|
|
|
|
/* If we didn't reserve the blocks, we're not allowed to punch them. */
|
|
if (!(iomap->flags & IOMAP_F_NEW))
|
|
return 0;
|
|
|
|
/*
|
|
* start_byte refers to the first unused block after a short write. If
|
|
* nothing was written, round offset down to point at the first block in
|
|
* the range.
|
|
*/
|
|
if (unlikely(!written))
|
|
start_byte = round_down(pos, blocksize);
|
|
else
|
|
start_byte = round_up(pos + written, blocksize);
|
|
end_byte = round_up(pos + length, blocksize);
|
|
|
|
/* Nothing to do if we've written the entire delalloc extent */
|
|
if (start_byte >= end_byte)
|
|
return 0;
|
|
|
|
return iomap_write_delalloc_release(inode, start_byte, end_byte,
|
|
punch);
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_file_buffered_write_punch_delalloc);
|
|
|
|
static loff_t iomap_unshare_iter(struct iomap_iter *iter)
|
|
{
|
|
struct iomap *iomap = &iter->iomap;
|
|
const struct iomap *srcmap = iomap_iter_srcmap(iter);
|
|
loff_t pos = iter->pos;
|
|
loff_t length = iomap_length(iter);
|
|
long status = 0;
|
|
loff_t written = 0;
|
|
|
|
/* don't bother with blocks that are not shared to start with */
|
|
if (!(iomap->flags & IOMAP_F_SHARED))
|
|
return length;
|
|
/* don't bother with holes or unwritten extents */
|
|
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
|
|
return length;
|
|
|
|
do {
|
|
unsigned long offset = offset_in_page(pos);
|
|
unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
|
|
struct folio *folio;
|
|
|
|
status = iomap_write_begin(iter, pos, bytes, &folio);
|
|
if (unlikely(status))
|
|
return status;
|
|
if (iter->iomap.flags & IOMAP_F_STALE)
|
|
break;
|
|
|
|
status = iomap_write_end(iter, pos, bytes, bytes, folio);
|
|
if (WARN_ON_ONCE(status == 0))
|
|
return -EIO;
|
|
|
|
cond_resched();
|
|
|
|
pos += status;
|
|
written += status;
|
|
length -= status;
|
|
|
|
balance_dirty_pages_ratelimited(iter->inode->i_mapping);
|
|
} while (length);
|
|
|
|
return written;
|
|
}
|
|
|
|
int
|
|
iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct iomap_iter iter = {
|
|
.inode = inode,
|
|
.pos = pos,
|
|
.len = len,
|
|
.flags = IOMAP_WRITE | IOMAP_UNSHARE,
|
|
};
|
|
int ret;
|
|
|
|
while ((ret = iomap_iter(&iter, ops)) > 0)
|
|
iter.processed = iomap_unshare_iter(&iter);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_file_unshare);
|
|
|
|
static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
|
|
{
|
|
const struct iomap *srcmap = iomap_iter_srcmap(iter);
|
|
loff_t pos = iter->pos;
|
|
loff_t length = iomap_length(iter);
|
|
loff_t written = 0;
|
|
|
|
/* already zeroed? we're done. */
|
|
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
|
|
return length;
|
|
|
|
do {
|
|
struct folio *folio;
|
|
int status;
|
|
size_t offset;
|
|
size_t bytes = min_t(u64, SIZE_MAX, length);
|
|
|
|
status = iomap_write_begin(iter, pos, bytes, &folio);
|
|
if (status)
|
|
return status;
|
|
if (iter->iomap.flags & IOMAP_F_STALE)
|
|
break;
|
|
|
|
offset = offset_in_folio(folio, pos);
|
|
if (bytes > folio_size(folio) - offset)
|
|
bytes = folio_size(folio) - offset;
|
|
|
|
folio_zero_range(folio, offset, bytes);
|
|
folio_mark_accessed(folio);
|
|
|
|
bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
|
|
if (WARN_ON_ONCE(bytes == 0))
|
|
return -EIO;
|
|
|
|
pos += bytes;
|
|
length -= bytes;
|
|
written += bytes;
|
|
} while (length > 0);
|
|
|
|
if (did_zero)
|
|
*did_zero = true;
|
|
return written;
|
|
}
|
|
|
|
int
|
|
iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct iomap_iter iter = {
|
|
.inode = inode,
|
|
.pos = pos,
|
|
.len = len,
|
|
.flags = IOMAP_ZERO,
|
|
};
|
|
int ret;
|
|
|
|
while ((ret = iomap_iter(&iter, ops)) > 0)
|
|
iter.processed = iomap_zero_iter(&iter, did_zero);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_zero_range);
|
|
|
|
int
|
|
iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
unsigned int blocksize = i_blocksize(inode);
|
|
unsigned int off = pos & (blocksize - 1);
|
|
|
|
/* Block boundary? Nothing to do */
|
|
if (!off)
|
|
return 0;
|
|
return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_truncate_page);
|
|
|
|
static loff_t iomap_folio_mkwrite_iter(struct iomap_iter *iter,
|
|
struct folio *folio)
|
|
{
|
|
loff_t length = iomap_length(iter);
|
|
int ret;
|
|
|
|
if (iter->iomap.flags & IOMAP_F_BUFFER_HEAD) {
|
|
ret = __block_write_begin_int(folio, iter->pos, length, NULL,
|
|
&iter->iomap);
|
|
if (ret)
|
|
return ret;
|
|
block_commit_write(&folio->page, 0, length);
|
|
} else {
|
|
WARN_ON_ONCE(!folio_test_uptodate(folio));
|
|
folio_mark_dirty(folio);
|
|
}
|
|
|
|
return length;
|
|
}
|
|
|
|
vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
|
|
{
|
|
struct iomap_iter iter = {
|
|
.inode = file_inode(vmf->vma->vm_file),
|
|
.flags = IOMAP_WRITE | IOMAP_FAULT,
|
|
};
|
|
struct folio *folio = page_folio(vmf->page);
|
|
ssize_t ret;
|
|
|
|
folio_lock(folio);
|
|
ret = folio_mkwrite_check_truncate(folio, iter.inode);
|
|
if (ret < 0)
|
|
goto out_unlock;
|
|
iter.pos = folio_pos(folio);
|
|
iter.len = ret;
|
|
while ((ret = iomap_iter(&iter, ops)) > 0)
|
|
iter.processed = iomap_folio_mkwrite_iter(&iter, folio);
|
|
|
|
if (ret < 0)
|
|
goto out_unlock;
|
|
folio_wait_stable(folio);
|
|
return VM_FAULT_LOCKED;
|
|
out_unlock:
|
|
folio_unlock(folio);
|
|
return block_page_mkwrite_return(ret);
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
|
|
|
|
static void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
|
|
size_t len, int error)
|
|
{
|
|
struct iomap_page *iop = to_iomap_page(folio);
|
|
|
|
if (error) {
|
|
folio_set_error(folio);
|
|
mapping_set_error(inode->i_mapping, error);
|
|
}
|
|
|
|
WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !iop);
|
|
WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) <= 0);
|
|
|
|
if (!iop || atomic_sub_and_test(len, &iop->write_bytes_pending))
|
|
folio_end_writeback(folio);
|
|
}
|
|
|
|
/*
|
|
* We're now finished for good with this ioend structure. Update the page
|
|
* state, release holds on bios, and finally free up memory. Do not use the
|
|
* ioend after this.
|
|
*/
|
|
static u32
|
|
iomap_finish_ioend(struct iomap_ioend *ioend, int error)
|
|
{
|
|
struct inode *inode = ioend->io_inode;
|
|
struct bio *bio = &ioend->io_inline_bio;
|
|
struct bio *last = ioend->io_bio, *next;
|
|
u64 start = bio->bi_iter.bi_sector;
|
|
loff_t offset = ioend->io_offset;
|
|
bool quiet = bio_flagged(bio, BIO_QUIET);
|
|
u32 folio_count = 0;
|
|
|
|
for (bio = &ioend->io_inline_bio; bio; bio = next) {
|
|
struct folio_iter fi;
|
|
|
|
/*
|
|
* For the last bio, bi_private points to the ioend, so we
|
|
* need to explicitly end the iteration here.
|
|
*/
|
|
if (bio == last)
|
|
next = NULL;
|
|
else
|
|
next = bio->bi_private;
|
|
|
|
/* walk all folios in bio, ending page IO on them */
|
|
bio_for_each_folio_all(fi, bio) {
|
|
iomap_finish_folio_write(inode, fi.folio, fi.length,
|
|
error);
|
|
folio_count++;
|
|
}
|
|
bio_put(bio);
|
|
}
|
|
/* The ioend has been freed by bio_put() */
|
|
|
|
if (unlikely(error && !quiet)) {
|
|
printk_ratelimited(KERN_ERR
|
|
"%s: writeback error on inode %lu, offset %lld, sector %llu",
|
|
inode->i_sb->s_id, inode->i_ino, offset, start);
|
|
}
|
|
return folio_count;
|
|
}
|
|
|
|
/*
|
|
* Ioend completion routine for merged bios. This can only be called from task
|
|
* contexts as merged ioends can be of unbound length. Hence we have to break up
|
|
* the writeback completions into manageable chunks to avoid long scheduler
|
|
* holdoffs. We aim to keep scheduler holdoffs down below 10ms so that we get
|
|
* good batch processing throughput without creating adverse scheduler latency
|
|
* conditions.
|
|
*/
|
|
void
|
|
iomap_finish_ioends(struct iomap_ioend *ioend, int error)
|
|
{
|
|
struct list_head tmp;
|
|
u32 completions;
|
|
|
|
might_sleep();
|
|
|
|
list_replace_init(&ioend->io_list, &tmp);
|
|
completions = iomap_finish_ioend(ioend, error);
|
|
|
|
while (!list_empty(&tmp)) {
|
|
if (completions > IOEND_BATCH_SIZE * 8) {
|
|
cond_resched();
|
|
completions = 0;
|
|
}
|
|
ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
|
|
list_del_init(&ioend->io_list);
|
|
completions += iomap_finish_ioend(ioend, error);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_finish_ioends);
|
|
|
|
/*
|
|
* We can merge two adjacent ioends if they have the same set of work to do.
|
|
*/
|
|
static bool
|
|
iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
|
|
{
|
|
if (ioend->io_bio->bi_status != next->io_bio->bi_status)
|
|
return false;
|
|
if ((ioend->io_flags & IOMAP_F_SHARED) ^
|
|
(next->io_flags & IOMAP_F_SHARED))
|
|
return false;
|
|
if ((ioend->io_type == IOMAP_UNWRITTEN) ^
|
|
(next->io_type == IOMAP_UNWRITTEN))
|
|
return false;
|
|
if (ioend->io_offset + ioend->io_size != next->io_offset)
|
|
return false;
|
|
/*
|
|
* Do not merge physically discontiguous ioends. The filesystem
|
|
* completion functions will have to iterate the physical
|
|
* discontiguities even if we merge the ioends at a logical level, so
|
|
* we don't gain anything by merging physical discontiguities here.
|
|
*
|
|
* We cannot use bio->bi_iter.bi_sector here as it is modified during
|
|
* submission so does not point to the start sector of the bio at
|
|
* completion.
|
|
*/
|
|
if (ioend->io_sector + (ioend->io_size >> 9) != next->io_sector)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
void
|
|
iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends)
|
|
{
|
|
struct iomap_ioend *next;
|
|
|
|
INIT_LIST_HEAD(&ioend->io_list);
|
|
|
|
while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend,
|
|
io_list))) {
|
|
if (!iomap_ioend_can_merge(ioend, next))
|
|
break;
|
|
list_move_tail(&next->io_list, &ioend->io_list);
|
|
ioend->io_size += next->io_size;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
|
|
|
|
static int
|
|
iomap_ioend_compare(void *priv, const struct list_head *a,
|
|
const struct list_head *b)
|
|
{
|
|
struct iomap_ioend *ia = container_of(a, struct iomap_ioend, io_list);
|
|
struct iomap_ioend *ib = container_of(b, struct iomap_ioend, io_list);
|
|
|
|
if (ia->io_offset < ib->io_offset)
|
|
return -1;
|
|
if (ia->io_offset > ib->io_offset)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
void
|
|
iomap_sort_ioends(struct list_head *ioend_list)
|
|
{
|
|
list_sort(NULL, ioend_list, iomap_ioend_compare);
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_sort_ioends);
|
|
|
|
static void iomap_writepage_end_bio(struct bio *bio)
|
|
{
|
|
struct iomap_ioend *ioend = bio->bi_private;
|
|
|
|
iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status));
|
|
}
|
|
|
|
/*
|
|
* Submit the final bio for an ioend.
|
|
*
|
|
* If @error is non-zero, it means that we have a situation where some part of
|
|
* the submission process has failed after we've marked pages for writeback
|
|
* and unlocked them. In this situation, we need to fail the bio instead of
|
|
* submitting it. This typically only happens on a filesystem shutdown.
|
|
*/
|
|
static int
|
|
iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend,
|
|
int error)
|
|
{
|
|
ioend->io_bio->bi_private = ioend;
|
|
ioend->io_bio->bi_end_io = iomap_writepage_end_bio;
|
|
|
|
if (wpc->ops->prepare_ioend)
|
|
error = wpc->ops->prepare_ioend(ioend, error);
|
|
if (error) {
|
|
/*
|
|
* If we're failing the IO now, just mark the ioend with an
|
|
* error and finish it. This will run IO completion immediately
|
|
* as there is only one reference to the ioend at this point in
|
|
* time.
|
|
*/
|
|
ioend->io_bio->bi_status = errno_to_blk_status(error);
|
|
bio_endio(ioend->io_bio);
|
|
return error;
|
|
}
|
|
|
|
submit_bio(ioend->io_bio);
|
|
return 0;
|
|
}
|
|
|
|
static struct iomap_ioend *
|
|
iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
|
|
loff_t offset, sector_t sector, struct writeback_control *wbc)
|
|
{
|
|
struct iomap_ioend *ioend;
|
|
struct bio *bio;
|
|
|
|
bio = bio_alloc_bioset(wpc->iomap.bdev, BIO_MAX_VECS,
|
|
REQ_OP_WRITE | wbc_to_write_flags(wbc),
|
|
GFP_NOFS, &iomap_ioend_bioset);
|
|
bio->bi_iter.bi_sector = sector;
|
|
wbc_init_bio(wbc, bio);
|
|
|
|
ioend = container_of(bio, struct iomap_ioend, io_inline_bio);
|
|
INIT_LIST_HEAD(&ioend->io_list);
|
|
ioend->io_type = wpc->iomap.type;
|
|
ioend->io_flags = wpc->iomap.flags;
|
|
ioend->io_inode = inode;
|
|
ioend->io_size = 0;
|
|
ioend->io_folios = 0;
|
|
ioend->io_offset = offset;
|
|
ioend->io_bio = bio;
|
|
ioend->io_sector = sector;
|
|
return ioend;
|
|
}
|
|
|
|
/*
|
|
* Allocate a new bio, and chain the old bio to the new one.
|
|
*
|
|
* Note that we have to perform the chaining in this unintuitive order
|
|
* so that the bi_private linkage is set up in the right direction for the
|
|
* traversal in iomap_finish_ioend().
|
|
*/
|
|
static struct bio *
|
|
iomap_chain_bio(struct bio *prev)
|
|
{
|
|
struct bio *new;
|
|
|
|
new = bio_alloc(prev->bi_bdev, BIO_MAX_VECS, prev->bi_opf, GFP_NOFS);
|
|
bio_clone_blkg_association(new, prev);
|
|
new->bi_iter.bi_sector = bio_end_sector(prev);
|
|
|
|
bio_chain(prev, new);
|
|
bio_get(prev); /* for iomap_finish_ioend */
|
|
submit_bio(prev);
|
|
return new;
|
|
}
|
|
|
|
static bool
|
|
iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t offset,
|
|
sector_t sector)
|
|
{
|
|
if ((wpc->iomap.flags & IOMAP_F_SHARED) !=
|
|
(wpc->ioend->io_flags & IOMAP_F_SHARED))
|
|
return false;
|
|
if (wpc->iomap.type != wpc->ioend->io_type)
|
|
return false;
|
|
if (offset != wpc->ioend->io_offset + wpc->ioend->io_size)
|
|
return false;
|
|
if (sector != bio_end_sector(wpc->ioend->io_bio))
|
|
return false;
|
|
/*
|
|
* Limit ioend bio chain lengths to minimise IO completion latency. This
|
|
* also prevents long tight loops ending page writeback on all the
|
|
* folios in the ioend.
|
|
*/
|
|
if (wpc->ioend->io_folios >= IOEND_BATCH_SIZE)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Test to see if we have an existing ioend structure that we could append to
|
|
* first; otherwise finish off the current ioend and start another.
|
|
*/
|
|
static void
|
|
iomap_add_to_ioend(struct inode *inode, loff_t pos, struct folio *folio,
|
|
struct iomap_page *iop, struct iomap_writepage_ctx *wpc,
|
|
struct writeback_control *wbc, struct list_head *iolist)
|
|
{
|
|
sector_t sector = iomap_sector(&wpc->iomap, pos);
|
|
unsigned len = i_blocksize(inode);
|
|
size_t poff = offset_in_folio(folio, pos);
|
|
|
|
if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, pos, sector)) {
|
|
if (wpc->ioend)
|
|
list_add(&wpc->ioend->io_list, iolist);
|
|
wpc->ioend = iomap_alloc_ioend(inode, wpc, pos, sector, wbc);
|
|
}
|
|
|
|
if (!bio_add_folio(wpc->ioend->io_bio, folio, len, poff)) {
|
|
wpc->ioend->io_bio = iomap_chain_bio(wpc->ioend->io_bio);
|
|
bio_add_folio(wpc->ioend->io_bio, folio, len, poff);
|
|
}
|
|
|
|
if (iop)
|
|
atomic_add(len, &iop->write_bytes_pending);
|
|
wpc->ioend->io_size += len;
|
|
wbc_account_cgroup_owner(wbc, &folio->page, len);
|
|
}
|
|
|
|
/*
|
|
* We implement an immediate ioend submission policy here to avoid needing to
|
|
* chain multiple ioends and hence nest mempool allocations which can violate
|
|
* the forward progress guarantees we need to provide. The current ioend we're
|
|
* adding blocks to is cached in the writepage context, and if the new block
|
|
* doesn't append to the cached ioend, it will create a new ioend and cache that
|
|
* instead.
|
|
*
|
|
* If a new ioend is created and cached, the old ioend is returned and queued
|
|
* locally for submission once the entire page is processed or an error has been
|
|
* detected. While ioends are submitted immediately after they are completed,
|
|
* batching optimisations are provided by higher level block plugging.
|
|
*
|
|
* At the end of a writeback pass, there will be a cached ioend remaining on the
|
|
* writepage context that the caller will need to submit.
|
|
*/
|
|
static int
|
|
iomap_writepage_map(struct iomap_writepage_ctx *wpc,
|
|
struct writeback_control *wbc, struct inode *inode,
|
|
struct folio *folio, u64 end_pos)
|
|
{
|
|
struct iomap_page *iop = iomap_page_create(inode, folio, 0);
|
|
struct iomap_ioend *ioend, *next;
|
|
unsigned len = i_blocksize(inode);
|
|
unsigned nblocks = i_blocks_per_folio(inode, folio);
|
|
u64 pos = folio_pos(folio);
|
|
int error = 0, count = 0, i;
|
|
LIST_HEAD(submit_list);
|
|
|
|
WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
|
|
|
|
/*
|
|
* Walk through the folio to find areas to write back. If we
|
|
* run off the end of the current map or find the current map
|
|
* invalid, grab a new one.
|
|
*/
|
|
for (i = 0; i < nblocks && pos < end_pos; i++, pos += len) {
|
|
if (iop && !test_bit(i, iop->uptodate))
|
|
continue;
|
|
|
|
error = wpc->ops->map_blocks(wpc, inode, pos);
|
|
if (error)
|
|
break;
|
|
trace_iomap_writepage_map(inode, &wpc->iomap);
|
|
if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE))
|
|
continue;
|
|
if (wpc->iomap.type == IOMAP_HOLE)
|
|
continue;
|
|
iomap_add_to_ioend(inode, pos, folio, iop, wpc, wbc,
|
|
&submit_list);
|
|
count++;
|
|
}
|
|
if (count)
|
|
wpc->ioend->io_folios++;
|
|
|
|
WARN_ON_ONCE(!wpc->ioend && !list_empty(&submit_list));
|
|
WARN_ON_ONCE(!folio_test_locked(folio));
|
|
WARN_ON_ONCE(folio_test_writeback(folio));
|
|
WARN_ON_ONCE(folio_test_dirty(folio));
|
|
|
|
/*
|
|
* We cannot cancel the ioend directly here on error. We may have
|
|
* already set other pages under writeback and hence we have to run I/O
|
|
* completion to mark the error state of the pages under writeback
|
|
* appropriately.
|
|
*/
|
|
if (unlikely(error)) {
|
|
/*
|
|
* Let the filesystem know what portion of the current page
|
|
* failed to map. If the page hasn't been added to ioend, it
|
|
* won't be affected by I/O completion and we must unlock it
|
|
* now.
|
|
*/
|
|
if (wpc->ops->discard_folio)
|
|
wpc->ops->discard_folio(folio, pos);
|
|
if (!count) {
|
|
folio_unlock(folio);
|
|
goto done;
|
|
}
|
|
}
|
|
|
|
folio_start_writeback(folio);
|
|
folio_unlock(folio);
|
|
|
|
/*
|
|
* Preserve the original error if there was one; catch
|
|
* submission errors here and propagate into subsequent ioend
|
|
* submissions.
|
|
*/
|
|
list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
|
|
int error2;
|
|
|
|
list_del_init(&ioend->io_list);
|
|
error2 = iomap_submit_ioend(wpc, ioend, error);
|
|
if (error2 && !error)
|
|
error = error2;
|
|
}
|
|
|
|
/*
|
|
* We can end up here with no error and nothing to write only if we race
|
|
* with a partial page truncate on a sub-page block sized filesystem.
|
|
*/
|
|
if (!count)
|
|
folio_end_writeback(folio);
|
|
done:
|
|
mapping_set_error(inode->i_mapping, error);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Write out a dirty page.
|
|
*
|
|
* For delalloc space on the page, we need to allocate space and flush it.
|
|
* For unwritten space on the page, we need to start the conversion to
|
|
* regular allocated space.
|
|
*/
|
|
static int iomap_do_writepage(struct folio *folio,
|
|
struct writeback_control *wbc, void *data)
|
|
{
|
|
struct iomap_writepage_ctx *wpc = data;
|
|
struct inode *inode = folio->mapping->host;
|
|
u64 end_pos, isize;
|
|
|
|
trace_iomap_writepage(inode, folio_pos(folio), folio_size(folio));
|
|
|
|
/*
|
|
* Refuse to write the folio out if we're called from reclaim context.
|
|
*
|
|
* This avoids stack overflows when called from deeply used stacks in
|
|
* random callers for direct reclaim or memcg reclaim. We explicitly
|
|
* allow reclaim from kswapd as the stack usage there is relatively low.
|
|
*
|
|
* This should never happen except in the case of a VM regression so
|
|
* warn about it.
|
|
*/
|
|
if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
|
|
PF_MEMALLOC))
|
|
goto redirty;
|
|
|
|
/*
|
|
* Is this folio beyond the end of the file?
|
|
*
|
|
* The folio index is less than the end_index, adjust the end_pos
|
|
* to the highest offset that this folio should represent.
|
|
* -----------------------------------------------------
|
|
* | file mapping | <EOF> |
|
|
* -----------------------------------------------------
|
|
* | Page ... | Page N-2 | Page N-1 | Page N | |
|
|
* ^--------------------------------^----------|--------
|
|
* | desired writeback range | see else |
|
|
* ---------------------------------^------------------|
|
|
*/
|
|
isize = i_size_read(inode);
|
|
end_pos = folio_pos(folio) + folio_size(folio);
|
|
if (end_pos > isize) {
|
|
/*
|
|
* Check whether the page to write out is beyond or straddles
|
|
* i_size or not.
|
|
* -------------------------------------------------------
|
|
* | file mapping | <EOF> |
|
|
* -------------------------------------------------------
|
|
* | Page ... | Page N-2 | Page N-1 | Page N | Beyond |
|
|
* ^--------------------------------^-----------|---------
|
|
* | | Straddles |
|
|
* ---------------------------------^-----------|--------|
|
|
*/
|
|
size_t poff = offset_in_folio(folio, isize);
|
|
pgoff_t end_index = isize >> PAGE_SHIFT;
|
|
|
|
/*
|
|
* Skip the page if it's fully outside i_size, e.g.
|
|
* due to a truncate operation that's in progress. We've
|
|
* cleaned this page and truncate will finish things off for
|
|
* us.
|
|
*
|
|
* Note that the end_index is unsigned long. If the given
|
|
* offset is greater than 16TB on a 32-bit system then if we
|
|
* checked if the page is fully outside i_size with
|
|
* "if (page->index >= end_index + 1)", "end_index + 1" would
|
|
* overflow and evaluate to 0. Hence this page would be
|
|
* redirtied and written out repeatedly, which would result in
|
|
* an infinite loop; the user program performing this operation
|
|
* would hang. Instead, we can detect this situation by
|
|
* checking if the page is totally beyond i_size or if its
|
|
* offset is just equal to the EOF.
|
|
*/
|
|
if (folio->index > end_index ||
|
|
(folio->index == end_index && poff == 0))
|
|
goto unlock;
|
|
|
|
/*
|
|
* The page straddles i_size. It must be zeroed out on each
|
|
* and every writepage invocation because it may be mmapped.
|
|
* "A file is mapped in multiples of the page size. For a file
|
|
* that is not a multiple of the page size, the remaining
|
|
* memory is zeroed when mapped, and writes to that region are
|
|
* not written out to the file."
|
|
*/
|
|
folio_zero_segment(folio, poff, folio_size(folio));
|
|
end_pos = isize;
|
|
}
|
|
|
|
return iomap_writepage_map(wpc, wbc, inode, folio, end_pos);
|
|
|
|
redirty:
|
|
folio_redirty_for_writepage(wbc, folio);
|
|
unlock:
|
|
folio_unlock(folio);
|
|
return 0;
|
|
}
|
|
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int
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iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
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struct iomap_writepage_ctx *wpc,
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const struct iomap_writeback_ops *ops)
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{
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int ret;
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wpc->ops = ops;
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ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc);
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if (!wpc->ioend)
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return ret;
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return iomap_submit_ioend(wpc, wpc->ioend, ret);
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}
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EXPORT_SYMBOL_GPL(iomap_writepages);
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static int __init iomap_init(void)
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{
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return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
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offsetof(struct iomap_ioend, io_inline_bio),
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BIOSET_NEED_BVECS);
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}
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fs_initcall(iomap_init);
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