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xfs: use bounce buffering direct I/O when the device requires stable pages

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Fix direct I/O on devices that require stable pages by asking iomap
to bounce buffer.  To support this, ioends are used for direct reads
in this case to provide a user context for copying data back from the
bounce buffer.

This fixes qemu when used on devices using T10 protection information
and probably other cases like iSCSI using data digests.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2026-01-26 06:53:46 +01:00 committed by Jens Axboe
parent c9d114846b
commit 3373503df0
2 changed files with 44 additions and 5 deletions
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8
fs/xfs/xfs_aops.c
View File

@ -103,7 +103,7 @@ xfs_ioend_put_open_zones(
* IO write completion.
*/
STATIC void
xfs_end_ioend(
xfs_end_ioend_write(
struct iomap_ioend *ioend)
{
struct xfs_inode *ip = XFS_I(ioend->io_inode);
@ -202,7 +202,11 @@ xfs_end_io(
io_list))) {
list_del_init(&ioend->io_list);
iomap_ioend_try_merge(ioend, &tmp);
xfs_end_ioend(ioend);
if (bio_op(&ioend->io_bio) == REQ_OP_READ)
iomap_finish_ioends(ioend,
blk_status_to_errno(ioend->io_bio.bi_status));
else
xfs_end_ioend_write(ioend);
cond_resched();
}
}

41
fs/xfs/xfs_file.c
View File

@ -224,12 +224,34 @@ xfs_ilock_iocb_for_write(
return 0;
}
/*
* Bounce buffering dio reads need a user context to copy back the data.
* Use an ioend to provide that.
*/
static void
xfs_dio_read_bounce_submit_io(
const struct iomap_iter *iter,
struct bio *bio,
loff_t file_offset)
{
iomap_init_ioend(iter->inode, bio, file_offset, IOMAP_IOEND_DIRECT);
bio->bi_end_io = xfs_end_bio;
submit_bio(bio);
}
static const struct iomap_dio_ops xfs_dio_read_bounce_ops = {
.submit_io = xfs_dio_read_bounce_submit_io,
.bio_set = &iomap_ioend_bioset,
};
STATIC ssize_t
xfs_file_dio_read(
struct kiocb *iocb,
struct iov_iter *to)
{
struct xfs_inode *ip = XFS_I(file_inode(iocb->ki_filp));
unsigned int dio_flags = 0;
const struct iomap_dio_ops *dio_ops = NULL;
ssize_t ret;
trace_xfs_file_direct_read(iocb, to);
@ -242,7 +264,12 @@ xfs_file_dio_read(
ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
if (ret)
return ret;
ret = iomap_dio_rw(iocb, to, &xfs_read_iomap_ops, NULL, 0, NULL, 0);
if (mapping_stable_writes(iocb->ki_filp->f_mapping)) {
dio_ops = &xfs_dio_read_bounce_ops;
dio_flags |= IOMAP_DIO_BOUNCE;
}
ret = iomap_dio_rw(iocb, to, &xfs_read_iomap_ops, dio_ops, dio_flags,
NULL, 0);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
return ret;
@ -703,6 +730,8 @@ xfs_file_dio_write_aligned(
xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
iolock = XFS_IOLOCK_SHARED;
}
if (mapping_stable_writes(iocb->ki_filp->f_mapping))
dio_flags |= IOMAP_DIO_BOUNCE;
trace_xfs_file_direct_write(iocb, from);
ret = iomap_dio_rw(iocb, from, ops, dops, dio_flags, ac, 0);
out_unlock:
@ -750,6 +779,7 @@ xfs_file_dio_write_atomic(
{
unsigned int iolock = XFS_IOLOCK_SHARED;
ssize_t ret, ocount = iov_iter_count(from);
unsigned int dio_flags = 0;
const struct iomap_ops *dops;
/*
@ -777,8 +807,10 @@ xfs_file_dio_write_atomic(
}
trace_xfs_file_direct_write(iocb, from);
ret = iomap_dio_rw(iocb, from, dops, &xfs_dio_write_ops,
0, NULL, 0);
if (mapping_stable_writes(iocb->ki_filp->f_mapping))
dio_flags |= IOMAP_DIO_BOUNCE;
ret = iomap_dio_rw(iocb, from, dops, &xfs_dio_write_ops, dio_flags,
NULL, 0);
/*
* The retry mechanism is based on the ->iomap_begin method returning
@ -867,6 +899,9 @@ xfs_file_dio_write_unaligned(
if (flags & IOMAP_DIO_FORCE_WAIT)
inode_dio_wait(VFS_I(ip));
if (mapping_stable_writes(iocb->ki_filp->f_mapping))
flags |= IOMAP_DIO_BOUNCE;
trace_xfs_file_direct_write(iocb, from);
ret = iomap_dio_rw(iocb, from, &xfs_direct_write_iomap_ops,
&xfs_dio_write_ops, flags, NULL, 0);