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Merge patch series "iomap preliminaries for large atomic write for xfs with CoW"

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Bring in the iomap changes required for xfs to support large atomic
write with CoW.

* patches from https://lore.kernel.org/r/20250303171120.2837067-1-john.g.garry@oracle.com:
  iomap: Lift blocksize restriction on atomic writes
  iomap: Support SW-based atomic writes
  iomap: Rename IOMAP_ATOMIC -> IOMAP_ATOMIC_HW

Link: https://lore.kernel.org/r/20250303171120.2837067-1-john.g.garry@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-03-06 11:00:18 +01:00
commit c7be0d72d5
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GPG Key ID: 91C61BC06578DCA2
5 changed files with 36 additions and 16 deletions
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20
Documentation/filesystems/iomap/operations.rst
View File

@ -514,8 +514,8 @@ IOMAP_WRITE`` with any combination of the following enhancements:
if the mapping is unwritten and the filesystem cannot handle zeroing
the unaligned regions without exposing stale contents.
* ``IOMAP_ATOMIC``: This write is being issued with torn-write
protection.
* ``IOMAP_ATOMIC_HW``: This write is being issued with torn-write
protection based on HW-offload support.
Only a single bio can be created for the write, and the write must
not be split into multiple I/O requests, i.e. flag REQ_ATOMIC must be
set.
@ -526,8 +526,20 @@ IOMAP_WRITE`` with any combination of the following enhancements:
conversion or copy on write), all updates for the entire file range
must be committed atomically as well.
Only one space mapping is allowed per untorn write.
Untorn writes must be aligned to, and must not be longer than, a
single file block.
Untorn writes may be longer than a single file block. In all cases,
the mapping start disk block must have at least the same alignment as
the write offset.
* ``IOMAP_ATOMIC_SW``: This write is being issued with torn-write
protection via a software mechanism provided by the filesystem.
All the disk block alignment and single bio restrictions which apply
to IOMAP_ATOMIC_HW do not apply here.
SW-based untorn writes would typically be used as a fallback when
HW-based untorn writes may not be issued, e.g. the range of the write
covers multiple extents, meaning that it is not possible to issue
a single bio.
All filesystem metadata updates for the entire file range must be
committed atomically as well.
Callers commonly hold ``i_rwsem`` in shared or exclusive mode before
calling this function.

2
fs/ext4/inode.c
View File

@ -3467,7 +3467,7 @@ static inline bool ext4_want_directio_fallback(unsigned flags, ssize_t written)
return false;
/* atomic writes are all-or-nothing */
if (flags & IOMAP_ATOMIC)
if (flags & IOMAP_ATOMIC_HW)
return false;
/* can only try again if we wrote nothing */

20
fs/iomap/direct-io.c
View File

@ -317,7 +317,7 @@ static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
* clearing the WRITE_THROUGH flag in the dio request.
*/
static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
const struct iomap *iomap, bool use_fua, bool atomic)
const struct iomap *iomap, bool use_fua, bool atomic_hw)
{
blk_opf_t opflags = REQ_SYNC | REQ_IDLE;
@ -329,7 +329,7 @@ static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
opflags |= REQ_FUA;
else
dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
if (atomic)
if (atomic_hw)
opflags |= REQ_ATOMIC;
return opflags;
@ -340,8 +340,8 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
const struct iomap *iomap = &iter->iomap;
struct inode *inode = iter->inode;
unsigned int fs_block_size = i_blocksize(inode), pad;
bool atomic_hw = iter->flags & IOMAP_ATOMIC_HW;
const loff_t length = iomap_length(iter);
bool atomic = iter->flags & IOMAP_ATOMIC;
loff_t pos = iter->pos;
blk_opf_t bio_opf;
struct bio *bio;
@ -351,7 +351,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
u64 copied = 0;
size_t orig_count;
if (atomic && length != fs_block_size)
if (atomic_hw && length != iter->len)
return -EINVAL;
if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
@ -428,7 +428,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
goto out;
}
bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua, atomic);
bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua, atomic_hw);
nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
do {
@ -461,7 +461,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
}
n = bio->bi_iter.bi_size;
if (WARN_ON_ONCE(atomic && n != length)) {
if (WARN_ON_ONCE(atomic_hw && n != length)) {
/*
* This bio should have covered the complete length,
* which it doesn't, so error. We may need to zero out
@ -652,9 +652,6 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
if (iocb->ki_flags & IOCB_NOWAIT)
iomi.flags |= IOMAP_NOWAIT;
if (iocb->ki_flags & IOCB_ATOMIC)
iomi.flags |= IOMAP_ATOMIC;
if (iov_iter_rw(iter) == READ) {
/* reads can always complete inline */
dio->flags |= IOMAP_DIO_INLINE_COMP;
@ -689,6 +686,11 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
iomi.flags |= IOMAP_OVERWRITE_ONLY;
}
if (dio_flags & IOMAP_DIO_ATOMIC_SW)
iomi.flags |= IOMAP_ATOMIC_SW;
else if (iocb->ki_flags & IOCB_ATOMIC)
iomi.flags |= IOMAP_ATOMIC_HW;
/* for data sync or sync, we need sync completion processing */
if (iocb_is_dsync(iocb)) {
dio->flags |= IOMAP_DIO_NEED_SYNC;

2
fs/iomap/trace.h
View File

@ -99,7 +99,7 @@ DEFINE_RANGE_EVENT(iomap_dio_rw_queued);
{ IOMAP_FAULT, "FAULT" }, \
{ IOMAP_DIRECT, "DIRECT" }, \
{ IOMAP_NOWAIT, "NOWAIT" }, \
{ IOMAP_ATOMIC, "ATOMIC" }
{ IOMAP_ATOMIC_HW, "ATOMIC_HW" }
#define IOMAP_F_FLAGS_STRINGS \
{ IOMAP_F_NEW, "NEW" }, \

8
include/linux/iomap.h
View File

@ -189,8 +189,9 @@ struct iomap_folio_ops {
#else
#define IOMAP_DAX 0
#endif /* CONFIG_FS_DAX */
#define IOMAP_ATOMIC (1 << 9)
#define IOMAP_ATOMIC_HW (1 << 9) /* HW-based torn-write protection */
#define IOMAP_DONTCACHE (1 << 10)
#define IOMAP_ATOMIC_SW (1 << 11)/* SW-based torn-write protection */
struct iomap_ops {
/*
@ -502,6 +503,11 @@ struct iomap_dio_ops {
*/
#define IOMAP_DIO_PARTIAL (1 << 2)
/*
* Use software-based torn-write protection.
*/
#define IOMAP_DIO_ATOMIC_SW (1 << 3)
ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
unsigned int dio_flags, void *private, size_t done_before);