linux/fs/xfs/xfs_aops.c

1085 lines
31 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* Copyright (c) 2016-2018 Christoph Hellwig.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_alloc.h"
#include "xfs_error.h"
#include "xfs_iomap.h"
#include "xfs_trace.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_bmap_btree.h"
#include "xfs_reflink.h"
#include <linux/writeback.h>
/*
* structure owned by writepages passed to individual writepage calls
*/
struct xfs_writepage_ctx {
struct xfs_bmbt_irec imap;
int fork;
unsigned int data_seq;
unsigned int cow_seq;
struct xfs_ioend *ioend;
};
struct block_device *
xfs_find_bdev_for_inode(
struct inode *inode)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
if (XFS_IS_REALTIME_INODE(ip))
return mp->m_rtdev_targp->bt_bdev;
else
return mp->m_ddev_targp->bt_bdev;
}
struct dax_device *
xfs_find_daxdev_for_inode(
struct inode *inode)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
if (XFS_IS_REALTIME_INODE(ip))
return mp->m_rtdev_targp->bt_daxdev;
else
return mp->m_ddev_targp->bt_daxdev;
}
static void
xfs_finish_page_writeback(
struct inode *inode,
struct bio_vec *bvec,
int error)
{
struct iomap_page *iop = to_iomap_page(bvec->bv_page);
if (error) {
SetPageError(bvec->bv_page);
mapping_set_error(inode->i_mapping, -EIO);
}
ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
ASSERT(!iop || atomic_read(&iop->write_count) > 0);
if (!iop || atomic_dec_and_test(&iop->write_count))
end_page_writeback(bvec->bv_page);
}
/*
* 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 void
xfs_destroy_ioend(
struct xfs_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;
bool quiet = bio_flagged(bio, BIO_QUIET);
for (bio = &ioend->io_inline_bio; bio; bio = next) {
struct bio_vec *bvec;
int i;
struct bvec_iter_all iter_all;
/*
* 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 each page on bio, ending page IO on them */
bio_for_each_segment_all(bvec, bio, i, iter_all)
xfs_finish_page_writeback(inode, bvec, error);
bio_put(bio);
}
if (unlikely(error && !quiet)) {
xfs_err_ratelimited(XFS_I(inode)->i_mount,
"writeback error on sector %llu", start);
}
}
/*
* Fast and loose check if this write could update the on-disk inode size.
*/
static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend)
{
return ioend->io_offset + ioend->io_size >
XFS_I(ioend->io_inode)->i_d.di_size;
}
STATIC int
xfs_setfilesize_trans_alloc(
struct xfs_ioend *ioend)
{
struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
struct xfs_trans *tp;
int error;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0,
XFS_TRANS_NOFS, &tp);
if (error)
return error;
ioend->io_append_trans = tp;
/*
* We may pass freeze protection with a transaction. So tell lockdep
* we released it.
*/
__sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS);
/*
* We hand off the transaction to the completion thread now, so
* clear the flag here.
*/
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
return 0;
}
/*
* Update on-disk file size now that data has been written to disk.
*/
STATIC int
__xfs_setfilesize(
struct xfs_inode *ip,
struct xfs_trans *tp,
xfs_off_t offset,
size_t size)
{
xfs_fsize_t isize;
xfs_ilock(ip, XFS_ILOCK_EXCL);
isize = xfs_new_eof(ip, offset + size);
if (!isize) {
xfs_iunlock(ip, XFS_ILOCK_EXCL);
xfs_trans_cancel(tp);
return 0;
}
trace_xfs_setfilesize(ip, offset, size);
ip->i_d.di_size = isize;
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
return xfs_trans_commit(tp);
}
int
xfs_setfilesize(
struct xfs_inode *ip,
xfs_off_t offset,
size_t size)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
int error;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
if (error)
return error;
return __xfs_setfilesize(ip, tp, offset, size);
}
STATIC int
xfs_setfilesize_ioend(
struct xfs_ioend *ioend,
int error)
{
struct xfs_inode *ip = XFS_I(ioend->io_inode);
struct xfs_trans *tp = ioend->io_append_trans;
/*
* The transaction may have been allocated in the I/O submission thread,
* thus we need to mark ourselves as being in a transaction manually.
* Similarly for freeze protection.
*/
current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
__sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
/* we abort the update if there was an IO error */
if (error) {
xfs_trans_cancel(tp);
return error;
}
return __xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
}
/*
* IO write completion.
*/
STATIC void
xfs_end_io(
struct work_struct *work)
{
struct xfs_ioend *ioend =
container_of(work, struct xfs_ioend, io_work);
struct xfs_inode *ip = XFS_I(ioend->io_inode);
xfs_off_t offset = ioend->io_offset;
size_t size = ioend->io_size;
int error;
/*
* Just clean up the in-memory strutures if the fs has been shut down.
*/
if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
error = -EIO;
goto done;
}
/*
* Clean up any COW blocks on an I/O error.
*/
error = blk_status_to_errno(ioend->io_bio->bi_status);
if (unlikely(error)) {
if (ioend->io_fork == XFS_COW_FORK)
xfs_reflink_cancel_cow_range(ip, offset, size, true);
goto done;
}
/*
* Success: commit the COW or unwritten blocks if needed.
*/
if (ioend->io_fork == XFS_COW_FORK)
error = xfs_reflink_end_cow(ip, offset, size);
else if (ioend->io_state == XFS_EXT_UNWRITTEN)
error = xfs_iomap_write_unwritten(ip, offset, size, false);
else
ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_append_trans);
done:
if (ioend->io_append_trans)
error = xfs_setfilesize_ioend(ioend, error);
xfs_destroy_ioend(ioend, error);
}
STATIC void
xfs_end_bio(
struct bio *bio)
{
struct xfs_ioend *ioend = bio->bi_private;
struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
if (ioend->io_fork == XFS_COW_FORK ||
ioend->io_state == XFS_EXT_UNWRITTEN)
queue_work(mp->m_unwritten_workqueue, &ioend->io_work);
else if (ioend->io_append_trans)
queue_work(mp->m_data_workqueue, &ioend->io_work);
else
xfs_destroy_ioend(ioend, blk_status_to_errno(bio->bi_status));
}
/*
* Fast revalidation of the cached writeback mapping. Return true if the current
* mapping is valid, false otherwise.
*/
static bool
xfs_imap_valid(
struct xfs_writepage_ctx *wpc,
struct xfs_inode *ip,
xfs_fileoff_t offset_fsb)
{
if (offset_fsb < wpc->imap.br_startoff ||
offset_fsb >= wpc->imap.br_startoff + wpc->imap.br_blockcount)
return false;
/*
* If this is a COW mapping, it is sufficient to check that the mapping
* covers the offset. Be careful to check this first because the caller
* can revalidate a COW mapping without updating the data seqno.
*/
if (wpc->fork == XFS_COW_FORK)
return true;
/*
* This is not a COW mapping. Check the sequence number of the data fork
* because concurrent changes could have invalidated the extent. Check
* the COW fork because concurrent changes since the last time we
* checked (and found nothing at this offset) could have added
* overlapping blocks.
*/
if (wpc->data_seq != READ_ONCE(ip->i_df.if_seq))
return false;
if (xfs_inode_has_cow_data(ip) &&
wpc->cow_seq != READ_ONCE(ip->i_cowfp->if_seq))
return false;
return true;
}
/*
* Pass in a dellalloc extent and convert it to real extents, return the real
* extent that maps offset_fsb in wpc->imap.
*
* The current page is held locked so nothing could have removed the block
* backing offset_fsb, although it could have moved from the COW to the data
* fork by another thread.
*/
static int
xfs_convert_blocks(
struct xfs_writepage_ctx *wpc,
struct xfs_inode *ip,
xfs_fileoff_t offset_fsb)
{
int error;
/*
* Attempt to allocate whatever delalloc extent currently backs
* offset_fsb and put the result into wpc->imap. Allocate in a loop
* because it may take several attempts to allocate real blocks for a
* contiguous delalloc extent if free space is sufficiently fragmented.
*/
do {
error = xfs_bmapi_convert_delalloc(ip, wpc->fork, offset_fsb,
&wpc->imap, wpc->fork == XFS_COW_FORK ?
&wpc->cow_seq : &wpc->data_seq);
if (error)
return error;
} while (wpc->imap.br_startoff + wpc->imap.br_blockcount <= offset_fsb);
return 0;
}
STATIC int
xfs_map_blocks(
struct xfs_writepage_ctx *wpc,
struct inode *inode,
loff_t offset)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
ssize_t count = i_blocksize(inode);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
xfs_fileoff_t cow_fsb = NULLFILEOFF;
struct xfs_bmbt_irec imap;
struct xfs_iext_cursor icur;
int retries = 0;
int error = 0;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
/*
* COW fork blocks can overlap data fork blocks even if the blocks
* aren't shared. COW I/O always takes precedent, so we must always
* check for overlap on reflink inodes unless the mapping is already a
* COW one, or the COW fork hasn't changed from the last time we looked
* at it.
*
* It's safe to check the COW fork if_seq here without the ILOCK because
* we've indirectly protected against concurrent updates: writeback has
* the page locked, which prevents concurrent invalidations by reflink
* and directio and prevents concurrent buffered writes to the same
* page. Changes to if_seq always happen under i_lock, which protects
* against concurrent updates and provides a memory barrier on the way
* out that ensures that we always see the current value.
*/
if (xfs_imap_valid(wpc, ip, offset_fsb))
return 0;
/*
* If we don't have a valid map, now it's time to get a new one for this
* offset. This will convert delayed allocations (including COW ones)
* into real extents. If we return without a valid map, it means we
* landed in a hole and we skip the block.
*/
retry:
xfs_ilock(ip, XFS_ILOCK_SHARED);
ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
(ip->i_df.if_flags & XFS_IFEXTENTS));
/*
* Check if this is offset is covered by a COW extents, and if yes use
* it directly instead of looking up anything in the data fork.
*/
if (xfs_inode_has_cow_data(ip) &&
xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap))
cow_fsb = imap.br_startoff;
if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
wpc->fork = XFS_COW_FORK;
goto allocate_blocks;
}
/*
* No COW extent overlap. Revalidate now that we may have updated
* ->cow_seq. If the data mapping is still valid, we're done.
*/
if (xfs_imap_valid(wpc, ip, offset_fsb)) {
xfs_iunlock(ip, XFS_ILOCK_SHARED);
return 0;
}
/*
* If we don't have a valid map, now it's time to get a new one for this
* offset. This will convert delayed allocations (including COW ones)
* into real extents.
*/
if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap))
imap.br_startoff = end_fsb; /* fake a hole past EOF */
wpc->data_seq = READ_ONCE(ip->i_df.if_seq);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
wpc->fork = XFS_DATA_FORK;
/* landed in a hole or beyond EOF? */
if (imap.br_startoff > offset_fsb) {
imap.br_blockcount = imap.br_startoff - offset_fsb;
imap.br_startoff = offset_fsb;
imap.br_startblock = HOLESTARTBLOCK;
imap.br_state = XFS_EXT_NORM;
}
/*
* Truncate to the next COW extent if there is one. This is the only
* opportunity to do this because we can skip COW fork lookups for the
* subsequent blocks in the mapping; however, the requirement to treat
* the COW range separately remains.
*/
if (cow_fsb != NULLFILEOFF &&
cow_fsb < imap.br_startoff + imap.br_blockcount)
imap.br_blockcount = cow_fsb - imap.br_startoff;
/* got a delalloc extent? */
if (imap.br_startblock != HOLESTARTBLOCK &&
isnullstartblock(imap.br_startblock))
goto allocate_blocks;
wpc->imap = imap;
trace_xfs_map_blocks_found(ip, offset, count, wpc->fork, &imap);
return 0;
allocate_blocks:
error = xfs_convert_blocks(wpc, ip, offset_fsb);
if (error) {
/*
* If we failed to find the extent in the COW fork we might have
* raced with a COW to data fork conversion or truncate.
* Restart the lookup to catch the extent in the data fork for
* the former case, but prevent additional retries to avoid
* looping forever for the latter case.
*/
if (error == -EAGAIN && wpc->fork == XFS_COW_FORK && !retries++)
goto retry;
ASSERT(error != -EAGAIN);
return error;
}
/*
* Due to merging the return real extent might be larger than the
* original delalloc one. Trim the return extent to the next COW
* boundary again to force a re-lookup.
*/
if (wpc->fork != XFS_COW_FORK && cow_fsb != NULLFILEOFF &&
cow_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount)
wpc->imap.br_blockcount = cow_fsb - wpc->imap.br_startoff;
ASSERT(wpc->imap.br_startoff <= offset_fsb);
ASSERT(wpc->imap.br_startoff + wpc->imap.br_blockcount > offset_fsb);
trace_xfs_map_blocks_alloc(ip, offset, count, wpc->fork, &imap);
return 0;
}
/*
* Submit the bio for an ioend. We are passed an ioend with a bio attached to
* it, and we submit that bio. The ioend may be used for multiple bio
* submissions, so we only want to allocate an append transaction for the ioend
* once. In the case of multiple bio submission, each bio will take an IO
* reference to the ioend to ensure that the ioend completion is only done once
* all bios have been submitted and the ioend is really done.
*
* If @fail is non-zero, it means that we have a situation where some part of
* the submission process has failed after we have marked paged for writeback
* and unlocked them. In this situation, we need to fail the bio and ioend
* rather than submit it to IO. This typically only happens on a filesystem
* shutdown.
*/
STATIC int
xfs_submit_ioend(
struct writeback_control *wbc,
struct xfs_ioend *ioend,
int status)
{
/* Convert CoW extents to regular */
if (!status && ioend->io_fork == XFS_COW_FORK) {
/*
* Yuk. This can do memory allocation, but is not a
* transactional operation so everything is done in GFP_KERNEL
* context. That can deadlock, because we hold pages in
* writeback state and GFP_KERNEL allocations can block on them.
* Hence we must operate in nofs conditions here.
*/
unsigned nofs_flag;
nofs_flag = memalloc_nofs_save();
status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
ioend->io_offset, ioend->io_size);
memalloc_nofs_restore(nofs_flag);
}
/* Reserve log space if we might write beyond the on-disk inode size. */
if (!status &&
(ioend->io_fork == XFS_COW_FORK ||
ioend->io_state != XFS_EXT_UNWRITTEN) &&
xfs_ioend_is_append(ioend) &&
!ioend->io_append_trans)
status = xfs_setfilesize_trans_alloc(ioend);
ioend->io_bio->bi_private = ioend;
ioend->io_bio->bi_end_io = xfs_end_bio;
ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
/*
* If we are 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.
*/
if (status) {
ioend->io_bio->bi_status = errno_to_blk_status(status);
bio_endio(ioend->io_bio);
return status;
}
ioend->io_bio->bi_write_hint = ioend->io_inode->i_write_hint;
submit_bio(ioend->io_bio);
return 0;
}
static struct xfs_ioend *
xfs_alloc_ioend(
struct inode *inode,
int fork,
xfs_exntst_t state,
xfs_off_t offset,
struct block_device *bdev,
sector_t sector)
{
struct xfs_ioend *ioend;
struct bio *bio;
bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &xfs_ioend_bioset);
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = sector;
ioend = container_of(bio, struct xfs_ioend, io_inline_bio);
INIT_LIST_HEAD(&ioend->io_list);
ioend->io_fork = fork;
ioend->io_state = state;
ioend->io_inode = inode;
ioend->io_size = 0;
ioend->io_offset = offset;
INIT_WORK(&ioend->io_work, xfs_end_io);
ioend->io_append_trans = NULL;
ioend->io_bio = bio;
return ioend;
}
/*
* Allocate a new bio, and chain the old bio to the new one.
*
* Note that we have to do perform the chaining in this unintuitive order
* so that the bi_private linkage is set up in the right direction for the
* traversal in xfs_destroy_ioend().
*/
static void
xfs_chain_bio(
struct xfs_ioend *ioend,
struct writeback_control *wbc,
struct block_device *bdev,
sector_t sector)
{
struct bio *new;
new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);
bio_set_dev(new, bdev);
new->bi_iter.bi_sector = sector;
bio_chain(ioend->io_bio, new);
bio_get(ioend->io_bio); /* for xfs_destroy_ioend */
ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
ioend->io_bio->bi_write_hint = ioend->io_inode->i_write_hint;
submit_bio(ioend->io_bio);
ioend->io_bio = new;
}
/*
* 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
xfs_add_to_ioend(
struct inode *inode,
xfs_off_t offset,
struct page *page,
struct iomap_page *iop,
struct xfs_writepage_ctx *wpc,
struct writeback_control *wbc,
struct list_head *iolist)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct block_device *bdev = xfs_find_bdev_for_inode(inode);
unsigned len = i_blocksize(inode);
unsigned poff = offset & (PAGE_SIZE - 1);
sector_t sector;
sector = xfs_fsb_to_db(ip, wpc->imap.br_startblock) +
((offset - XFS_FSB_TO_B(mp, wpc->imap.br_startoff)) >> 9);
if (!wpc->ioend ||
wpc->fork != wpc->ioend->io_fork ||
wpc->imap.br_state != wpc->ioend->io_state ||
sector != bio_end_sector(wpc->ioend->io_bio) ||
offset != wpc->ioend->io_offset + wpc->ioend->io_size) {
if (wpc->ioend)
list_add(&wpc->ioend->io_list, iolist);
wpc->ioend = xfs_alloc_ioend(inode, wpc->fork,
wpc->imap.br_state, offset, bdev, sector);
}
if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) {
if (iop)
atomic_inc(&iop->write_count);
if (bio_full(wpc->ioend->io_bio))
xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
bio_add_page(wpc->ioend->io_bio, page, len, poff);
}
wpc->ioend->io_size += len;
}
STATIC void
xfs_vm_invalidatepage(
struct page *page,
unsigned int offset,
unsigned int length)
{
trace_xfs_invalidatepage(page->mapping->host, page, offset, length);
iomap_invalidatepage(page, offset, length);
}
/*
* If the page has delalloc blocks on it, we need to punch them out before we
* invalidate the page. If we don't, we leave a stale delalloc mapping on the
* inode that can trip up a later direct I/O read operation on the same region.
*
* We prevent this by truncating away the delalloc regions on the page. Because
* they are delalloc, we can do this without needing a transaction. Indeed - if
* we get ENOSPC errors, we have to be able to do this truncation without a
* transaction as there is no space left for block reservation (typically why we
* see a ENOSPC in writeback).
*/
STATIC void
xfs_aops_discard_page(
struct page *page)
{
struct inode *inode = page->mapping->host;
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
loff_t offset = page_offset(page);
xfs_fileoff_t start_fsb = XFS_B_TO_FSBT(mp, offset);
int error;
if (XFS_FORCED_SHUTDOWN(mp))
goto out_invalidate;
xfs_alert(mp,
"page discard on page "PTR_FMT", inode 0x%llx, offset %llu.",
page, ip->i_ino, offset);
error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
PAGE_SIZE / i_blocksize(inode));
if (error && !XFS_FORCED_SHUTDOWN(mp))
xfs_alert(mp, "page discard unable to remove delalloc mapping.");
out_invalidate:
xfs_vm_invalidatepage(page, 0, PAGE_SIZE);
}
/*
* We implement an immediate ioend submission policy here to avoid needing to
* chain multiple ioends and hence nest mempool allocations which can violate
* forward progress guarantees we need to provide. The current ioend we are
* adding blocks to is cached on the writepage context, and if the new block
* does not 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
xfs_writepage_map(
struct xfs_writepage_ctx *wpc,
struct writeback_control *wbc,
struct inode *inode,
struct page *page,
uint64_t end_offset)
{
LIST_HEAD(submit_list);
struct iomap_page *iop = to_iomap_page(page);
unsigned len = i_blocksize(inode);
struct xfs_ioend *ioend, *next;
uint64_t file_offset; /* file offset of page */
int error = 0, count = 0, i;
ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
ASSERT(!iop || atomic_read(&iop->write_count) == 0);
/*
* Walk through the page 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, file_offset = page_offset(page);
i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
i++, file_offset += len) {
if (iop && !test_bit(i, iop->uptodate))
continue;
error = xfs_map_blocks(wpc, inode, file_offset);
if (error)
break;
if (wpc->imap.br_startblock == HOLESTARTBLOCK)
continue;
xfs_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
&submit_list);
count++;
}
ASSERT(wpc->ioend || list_empty(&submit_list));
ASSERT(PageLocked(page));
ASSERT(!PageWriteback(page));
/*
* On error, we have to fail the ioend here because we may have set
* pages under writeback, we have to make sure we run IO completion to
* mark the error state of the IO appropriately, so we can't cancel the
* ioend directly here. That means we have to mark this page as under
* writeback if we included any blocks from it in the ioend chain so
* that completion treats it correctly.
*
* If we didn't include the page in the ioend, the on error we can
* simply discard and unlock it as there are no other users of the page
* now. The caller will still need to trigger submission of outstanding
* ioends on the writepage context so they are treated correctly on
* error.
*/
if (unlikely(error)) {
if (!count) {
xfs_aops_discard_page(page);
ClearPageUptodate(page);
unlock_page(page);
goto done;
}
/*
* If the page was not fully cleaned, we need to ensure that the
* higher layers come back to it correctly. That means we need
* to keep the page dirty, and for WB_SYNC_ALL writeback we need
* to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed
* so another attempt to write this page in this writeback sweep
* will be made.
*/
set_page_writeback_keepwrite(page);
} else {
clear_page_dirty_for_io(page);
set_page_writeback(page);
}
unlock_page(page);
/*
* Preserve the original error if there was one, otherwise 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 = xfs_submit_ioend(wbc, 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)
end_page_writeback(page);
done:
mapping_set_error(page->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
xfs_do_writepage(
struct page *page,
struct writeback_control *wbc,
void *data)
{
struct xfs_writepage_ctx *wpc = data;
struct inode *inode = page->mapping->host;
loff_t offset;
uint64_t end_offset;
pgoff_t end_index;
trace_xfs_writepage(inode, page, 0, 0);
/*
* Refuse to write the page out if we are 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;
/*
* Given that we do not allow direct reclaim to call us, we should
* never be called while in a filesystem transaction.
*/
if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
goto redirty;
/*
* Is this page beyond the end of the file?
*
* The page index is less than the end_index, adjust the end_offset
* to the highest offset that this page should represent.
* -----------------------------------------------------
* | file mapping | <EOF> |
* -----------------------------------------------------
* | Page ... | Page N-2 | Page N-1 | Page N | |
* ^--------------------------------^----------|--------
* | desired writeback range | see else |
* ---------------------------------^------------------|
*/
offset = i_size_read(inode);
end_index = offset >> PAGE_SHIFT;
if (page->index < end_index)
end_offset = (xfs_off_t)(page->index + 1) << PAGE_SHIFT;
else {
/*
* 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 |
* ---------------------------------^-----------|--------|
*/
unsigned offset_into_page = offset & (PAGE_SIZE - 1);
/*
* Skip the page if it is fully outside i_size, e.g. due to a
* truncate operation that is in progress. We must redirty the
* page so that reclaim stops reclaiming it. Otherwise
* xfs_vm_releasepage() is called on it and gets confused.
*
* Note that the end_index is unsigned long, it would overflow
* if the given offset is greater than 16TB on 32-bit system
* and if we do check the page is fully outside i_size or not
* via "if (page->index >= end_index + 1)" as "end_index + 1"
* will be evaluated to 0. Hence this page will be redirtied
* and be written out repeatedly which would result in an
* infinite loop, the user program that perform this operation
* will hang. Instead, we can verify this situation by checking
* if the page to write is totally beyond the i_size or if it's
* offset is just equal to the EOF.
*/
if (page->index > end_index ||
(page->index == end_index && offset_into_page == 0))
goto redirty;
/*
* 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."
*/
zero_user_segment(page, offset_into_page, PAGE_SIZE);
/* Adjust the end_offset to the end of file */
end_offset = offset;
}
return xfs_writepage_map(wpc, wbc, inode, page, end_offset);
redirty:
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}
STATIC int
xfs_vm_writepage(
struct page *page,
struct writeback_control *wbc)
{
struct xfs_writepage_ctx wpc = { };
int ret;
ret = xfs_do_writepage(page, wbc, &wpc);
if (wpc.ioend)
ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
return ret;
}
STATIC int
xfs_vm_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
struct xfs_writepage_ctx wpc = { };
int ret;
xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc);
if (wpc.ioend)
ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
return ret;
}
STATIC int
xfs_dax_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
return dax_writeback_mapping_range(mapping,
xfs_find_bdev_for_inode(mapping->host), wbc);
}
STATIC int
xfs_vm_releasepage(
struct page *page,
gfp_t gfp_mask)
{
trace_xfs_releasepage(page->mapping->host, page, 0, 0);
return iomap_releasepage(page, gfp_mask);
}
STATIC sector_t
xfs_vm_bmap(
struct address_space *mapping,
sector_t block)
{
struct xfs_inode *ip = XFS_I(mapping->host);
trace_xfs_vm_bmap(ip);
/*
* The swap code (ab-)uses ->bmap to get a block mapping and then
* bypasses the file system for actual I/O. We really can't allow
* that on reflinks inodes, so we have to skip out here. And yes,
* 0 is the magic code for a bmap error.
*
* Since we don't pass back blockdev info, we can't return bmap
* information for rt files either.
*/
if (xfs_is_cow_inode(ip) || XFS_IS_REALTIME_INODE(ip))
return 0;
return iomap_bmap(mapping, block, &xfs_iomap_ops);
}
STATIC int
xfs_vm_readpage(
struct file *unused,
struct page *page)
{
trace_xfs_vm_readpage(page->mapping->host, 1);
return iomap_readpage(page, &xfs_iomap_ops);
}
STATIC int
xfs_vm_readpages(
struct file *unused,
struct address_space *mapping,
struct list_head *pages,
unsigned nr_pages)
{
trace_xfs_vm_readpages(mapping->host, nr_pages);
return iomap_readpages(mapping, pages, nr_pages, &xfs_iomap_ops);
}
static int
xfs_iomap_swapfile_activate(
struct swap_info_struct *sis,
struct file *swap_file,
sector_t *span)
{
sis->bdev = xfs_find_bdev_for_inode(file_inode(swap_file));
return iomap_swapfile_activate(sis, swap_file, span, &xfs_iomap_ops);
}
const struct address_space_operations xfs_address_space_operations = {
.readpage = xfs_vm_readpage,
.readpages = xfs_vm_readpages,
.writepage = xfs_vm_writepage,
.writepages = xfs_vm_writepages,
.set_page_dirty = iomap_set_page_dirty,
.releasepage = xfs_vm_releasepage,
.invalidatepage = xfs_vm_invalidatepage,
.bmap = xfs_vm_bmap,
.direct_IO = noop_direct_IO,
.migratepage = iomap_migrate_page,
.is_partially_uptodate = iomap_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
.swap_activate = xfs_iomap_swapfile_activate,
};
const struct address_space_operations xfs_dax_aops = {
.writepages = xfs_dax_writepages,
.direct_IO = noop_direct_IO,
.set_page_dirty = noop_set_page_dirty,
.invalidatepage = noop_invalidatepage,
.swap_activate = xfs_iomap_swapfile_activate,
};