iomap: rework IOMAP atomic flags

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Flag IOMAP_ATOMIC_SW is not really required. The idea of having this flag
is that the FS ->iomap_begin callback could check if this flag is set to
decide whether to do a SW (FS-based) atomic write. But the FS can set
which ->iomap_begin callback it wants when deciding to do a FS-based
atomic write.

Furthermore, it was thought that IOMAP_ATOMIC_HW is not a proper name, as
the block driver can use SW-methods to emulate an atomic write. So change
back to IOMAP_ATOMIC.

The ->iomap_begin callback needs though to indicate to iomap core that
REQ_ATOMIC needs to be set, so add IOMAP_F_ATOMIC_BIO for that.

These changes were suggested by Christoph Hellwig and Dave Chinner.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250320120250.4087011-4-john.g.garry@oracle.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

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John Garry 2025-03-20 12:02:50 +00:00 • committed by Christian Brauner

parent aacd436e40

commit 370a6de765

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6 changed files with 37 additions and 30 deletions

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33

Documentation/filesystems/iomap/operations.rst

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6

fs/ext4/inode.c

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8

fs/iomap/direct-io.c

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2

fs/iomap/trace.h

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4

fs/xfs/xfs_iomap.c

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12

include/linux/iomap.h

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