[PATCH v2 01/11] iomap: Rename IOMAP_ATOMIC -> IOMAP_ATOMIC_HW

John Garry
2025-02-13T13:57:18Z

In future xfs will support a CoW-based atomic write, so rename
IOMAP_ATOMIC -> IOMAP_ATOMIC_HW to be clear which mode is being used.

Also relocate setting of IOMAP_ATOMIC_HW to the write path in
__iomap_dio_rw(), to be clear that this flag is only relevant to writes

Signed-off-by: John Garry <john.g.garry@oracle.com>
---
Documentation/filesystems/iomap/operations.rst | 4 ++--
fs/ext4/inode.c | 2 +-
fs/iomap/direct-io.c | 18 +++++++++---------
fs/iomap/trace.h | 2 +-
include/linux/iomap.h | 2 +-
5 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst
index 2c7f5df9d8b0..82bfe0e8c08e 100644
--- a/Documentation/filesystems/iomap/operations.rst
+++ b/Documentation/filesystems/iomap/operations.rst
@@ -513,8 +513,8 @@ 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.
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7c54ae5fcbd4..ba2f1e3db7c7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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 */
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index b521eb15759e..f87c4277e738 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -271,7 +271,7 @@ 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;

@@ -283,7 +283,7 @@ 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;
@@ -295,8 +295,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
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;
@@ -306,7 +306,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
size_t copied = 0;
size_t orig_count;

- if (atomic && length != fs_block_size)
+ if (atomic_hw && length != fs_block_size)
return -EINVAL;

if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
@@ -383,7 +383,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
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 {
@@ -416,7 +416,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
}

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
@@ -610,9 +610,6 @@ __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;
@@ -647,6 +644,9 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
iomi.flags |= IOMAP_OVERWRITE_ONLY;
}

+ 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;
diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
index 4118a42cdab0..0c73d91c0485 100644
--- a/fs/iomap/trace.h
+++ b/fs/iomap/trace.h
@@ -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" }, \
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 75bf54e76f3b..e7aa05503763 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -182,7 +182,7 @@ 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 */

struct iomap_ops {
/*
--
2.31.1