// 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_iomap.h"
#include "xfs_trace.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_reflink.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
struct xfs_writepage_ctx {
struct iomap_writepage_ctx ctx;
unsigned int data_seq;
unsigned int cow_seq;
};
static inline struct xfs_writepage_ctx *
XFS_WPC(struct iomap_writepage_ctx *ctx)
{
return container_of(ctx, struct xfs_writepage_ctx, ctx);
}
/*
* Fast and loose check if this write could update the on-disk inode size.
*/
static inline bool xfs_ioend_is_append(struct iomap_ioend *ioend)
{
return ioend->io_offset + ioend->io_size >
XFS_I(ioend->io_inode)->i_disk_size;
}
/*
* Update on-disk file size now that data has been written to disk.
*/
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;
xfs_fsize_t isize;
int error;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
if (error)
return error;
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_disk_size = isize;
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
return xfs_trans_commit(tp);
}
/*
* IO write completion.
*/
STATIC void
xfs_end_ioend(
struct iomap_ioend *ioend)
{
struct xfs_inode *ip = XFS_I(ioend->io_inode);
struct xfs_mount *mp = ip->i_mount;
xfs_off_t offset = ioend->io_offset;
size_t size = ioend->io_size;
unsigned int nofs_flag;
int error;
/*
* We can allocate memory here while doing writeback on behalf of
* memory reclaim. To avoid memory allocation deadlocks set the
* task-wide nofs context for the following operations.
*/
nofs_flag = memalloc_nofs_save();
/*
* Just clean up the in-memory structures if the fs has been shut down.
*/
if (xfs_is_shutdown(mp)) {
error = -EIO;
goto done;
}
/*
* Clean up all COW blocks and underlying data fork delalloc blocks on
* I/O error. The delalloc punch is required because this ioend was
* mapped to blocks in the COW fork and the associated pages are no
* longer dirty. If we don't remove delalloc blocks here, they become
* stale and can corrupt free space accounting on unmount.
*/
error = blk_status_to_errno(ioend->io_bio.bi_status);
if (unlikely(error)) {
if (ioend->io_flags & IOMAP_F_SHARED) {
xfs_reflink_cancel_cow_range(ip, offset, size, true);
xfs_bmap_punch_delalloc_range(ip, offset,
offset + size);
}
goto done;
}
/*
* Success: commit the COW or unwritten blocks if needed.
*/
if (ioend->io_flags & IOMAP_F_SHARED)
error = xfs_reflink_end_cow(ip, offset, size);
else if (ioend->io_type == IOMAP_UNWRITTEN)
error = xfs_iomap_write_unwritten(ip, offset, size, false);
if (!error && xfs_ioend_is_append(ioend))
error = xfs_setfilesize(ip, ioend->io_offset, ioend->io_size);
done:
iomap_finish_ioends(ioend, error);
memalloc_nofs_restore(nofs_flag);
}
/*
* Finish all pending IO completions that require transactional modifications.
*
* We try to merge physical and logically contiguous ioends before completion to
* minimise the number of transactions we need to perform during IO completion.
* Both unwritten extent conversion and COW remapping need to iterate and modify
* one physical extent at a time, so we gain nothing by merging physically
* discontiguous extents here.
*
* The ioend chain length that we can be processing here is largely unbound in
* length and we may have to perform significant amounts of work on each ioend
* to complete it. Hence we have to be careful about holding the CPU for too
* long in this loop.
*/
void
xfs_end_io(
struct work_struct *work)
{
struct xfs_inode *ip =
container_of(work, struct xfs_inode, i_ioend_work);
struct iomap_ioend *ioend;
struct list_head tmp;
unsigned long flags;
spin_lock_irqsave(&ip->i_ioend_lock, flags);
list_replace_init(&ip->i_ioend_list, &tmp);
spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
iomap_sort_ioends(&tmp);
while ((ioend = list_first_entry_or_null(&tmp, struct iomap_ioend,
io_list))) {
list_del_init(&ioend->io_list);
iomap_ioend_try_merge(ioend, &tmp);
xfs_end_ioend(ioend);
cond_resched();
}
}
STATIC void
xfs_end_bio(
struct bio *bio)
{
struct iomap_ioend *ioend = iomap_ioend_from_bio(bio);
struct xfs_inode *ip = XFS_I(ioend->io_inode);
unsigned long flags;
spin_lock_irqsave(&ip->i_ioend_lock, flags);
if (list_empty(&ip->i_ioend_list))
WARN_ON_ONCE(!queue_work(ip->i_mount->m_unwritten_workqueue,
&ip->i_ioend_work));
list_add_tail(&ioend->io_list, &ip->i_ioend_list);
spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
}
/*
* Fast revalidation of the cached writeback mapping. Return true if the current
* mapping is valid, false otherwise.
*/
static bool
xfs_imap_valid(
struct iomap_writepage_ctx *wpc,
struct xfs_inode *ip,
loff_t offset)
{
if (offset < wpc->iomap.offset ||
offset >= wpc->iomap.offset + wpc->iomap.length)
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->iomap.flags & IOMAP_F_SHARED)
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 (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq)) {
trace_xfs_wb_data_iomap_invalid(ip, &wpc->iomap,
XFS_WPC(wpc)->data_seq, XFS_DATA_FORK);
return false;
}
if (xfs_inode_has_cow_data(ip) &&
XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) {
trace_xfs_wb_cow_iomap_invalid(ip, &wpc->iomap,
XFS_WPC(wpc)->cow_seq, XFS_COW_FORK);
return false;
}
return true;
}
static int
xfs_map_blocks(
struct iomap_writepage_ctx *wpc,
struct inode *inode,
loff_t offset,
unsigned int len)
{
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;
int whichfork;
struct xfs_bmbt_irec imap;
struct xfs_iext_cursor icur;
int retries = 0;
int error = 0;
unsigned int *seq;
if (xfs_is_shutdown(mp))
return -EIO;
XFS_ERRORTAG_DELAY(mp, XFS_ERRTAG_WB_DELAY_MS);
/*
* 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))
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:
cow_fsb = NULLFILEOFF;
whichfork = XFS_DATA_FORK;
xfs_ilock(ip, XFS_ILOCK_SHARED);
ASSERT(!xfs_need_iread_extents(&ip->i_df));
/*
* 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) {
XFS_WPC(wpc)->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
whichfork = 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)) {
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 */
XFS_WPC(wpc)->data_seq = READ_ONCE(ip->i_df.if_seq);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
/* 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;
xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0, 0, XFS_WPC(wpc)->data_seq);
trace_xfs_map_blocks_found(ip, offset, count, whichfork, &imap);
return 0;
allocate_blocks:
/*
* Convert a dellalloc extent to a real one. 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.
*/
if (whichfork == XFS_COW_FORK)
seq = &XFS_WPC(wpc)->cow_seq;
else
seq = &XFS_WPC(wpc)->data_seq;
error = xfs_bmapi_convert_delalloc(ip, whichfork, offset,
&wpc->iomap, seq);
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 && whichfork == 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 (whichfork != XFS_COW_FORK && cow_fsb != NULLFILEOFF) {
loff_t cow_offset = XFS_FSB_TO_B(mp, cow_fsb);
if (cow_offset < wpc->iomap.offset + wpc->iomap.length)
wpc->iomap.length = cow_offset - wpc->iomap.offset;
}
ASSERT(wpc->iomap.offset <= offset);
ASSERT(wpc->iomap.offset + wpc->iomap.length > offset);
trace_xfs_map_blocks_alloc(ip, offset, count, whichfork, &imap);
return 0;
}
static int
xfs_prepare_ioend(
struct iomap_ioend *ioend,
int status)
{
unsigned int nofs_flag;
/*
* We can allocate memory here while doing writeback on behalf of
* memory reclaim. To avoid memory allocation deadlocks set the
* task-wide nofs context for the following operations.
*/
nofs_flag = memalloc_nofs_save();
/* Convert CoW extents to regular */
if (!status && (ioend->io_flags & IOMAP_F_SHARED)) {
status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
ioend->io_offset, ioend->io_size);
}
memalloc_nofs_restore(nofs_flag);
/* send ioends that might require a transaction to the completion wq */
if (xfs_ioend_is_append(ioend) || ioend->io_type == IOMAP_UNWRITTEN ||
(ioend->io_flags & IOMAP_F_SHARED))
ioend->io_bio.bi_end_io = xfs_end_bio;
return status;
}
/*
* If the folio has delalloc blocks on it, the caller is asking us to punch them
* out. If we don't, we can leave a stale delalloc mapping covered by a clean
* page that needs to be dirtied again before the delalloc mapping can be
* converted. This stale delalloc mapping 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 folio. 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_discard_folio(
struct folio *folio,
loff_t pos)
{
struct xfs_inode *ip = XFS_I(folio->mapping->host);
struct xfs_mount *mp = ip->i_mount;
if (xfs_is_shutdown(mp))
return;
xfs_alert_ratelimited(mp,
"page discard on page "PTR_FMT", inode 0x%llx, pos %llu.",
folio, ip->i_ino, pos);
/*
* The end of the punch range is always the offset of the first
* byte of the next folio. Hence the end offset is only dependent on the
* folio itself and not the start offset that is passed in.
*/
xfs_bmap_punch_delalloc_range(ip, pos,
folio_pos(folio) + folio_size(folio));
}
static const struct iomap_writeback_ops xfs_writeback_ops = {
.map_blocks = xfs_map_blocks,
.prepare_ioend = xfs_prepare_ioend,
.discard_folio = xfs_discard_folio,
};
STATIC int
xfs_vm_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
struct xfs_writepage_ctx wpc = { };
xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops);
}
STATIC int
xfs_dax_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
struct xfs_inode *ip = XFS_I(mapping->host);
xfs_iflags_clear(ip, XFS_ITRUNCATED);
return dax_writeback_mapping_range(mapping,
xfs_inode_buftarg(ip)->bt_daxdev, wbc);
}
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_read_iomap_ops);
}
STATIC int
xfs_vm_read_folio(
struct file *unused,
struct folio *folio)
{
return iomap_read_folio(folio, &xfs_read_iomap_ops);
}
STATIC void
xfs_vm_readahead(
struct readahead_control *rac)
{
iomap_readahead(rac, &xfs_read_iomap_ops);
}
static int
xfs_iomap_swapfile_activate(
struct swap_info_struct *sis,
struct file *swap_file,
sector_t *span)
{
sis->bdev = xfs_inode_buftarg(XFS_I(file_inode(swap_file)))->bt_bdev;
return iomap_swapfile_activate(sis, swap_file, span,
&xfs_read_iomap_ops);
}
const struct address_space_operations xfs_address_space_operations = {
.read_folio = xfs_vm_read_folio,
.readahead = xfs_vm_readahead,
.writepages = xfs_vm_writepages,
.dirty_folio = iomap_dirty_folio,
.release_folio = iomap_release_folio,
.invalidate_folio = iomap_invalidate_folio,
.bmap = xfs_vm_bmap,
.migrate_folio = filemap_migrate_folio,
.is_partially_uptodate = iomap_is_partially_uptodate,
.error_remove_folio = generic_error_remove_folio,
.swap_activate = xfs_iomap_swapfile_activate,
};
const struct address_space_operations xfs_dax_aops = {
.writepages = xfs_dax_writepages,
.dirty_folio = noop_dirty_folio,
.swap_activate = xfs_iomap_swapfile_activate,
};
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