| 370a6de7 | 20-Mar-2025 |
John Garry <john.g.garry@oracle.com> |
iomap: rework IOMAP atomic flags
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
iomap: rework IOMAP atomic flags
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>
show more ...
|
| 794ca29d | 03-Mar-2025 |
John Garry <john.g.garry@oracle.com> |
iomap: Support SW-based atomic writes
Currently atomic write support requires dedicated HW support. This imposes
a restriction on the filesystem that disk blocks need to be aligned and
contiguously
iomap: Support SW-based atomic writes
Currently atomic write support requires dedicated HW support. This imposes
a restriction on the filesystem that disk blocks need to be aligned and
contiguously mapped to FS blocks to issue atomic writes.
XFS has no method to guarantee FS block alignment for regular,
non-RT files. As such, atomic writes are currently limited to 1x FS block
there.
To deal with the scenario that we are issuing an atomic write over
misaligned or discontiguous data blocks - and raise the atomic write size
limit - support a SW-based software emulated atomic write mode. For XFS,
this SW-based atomic writes would use CoW support to issue emulated untorn
writes.
It is the responsibility of the FS to detect discontiguous atomic writes
and switch to IOMAP_DIO_ATOMIC_SW mode and retry the write. Indeed,
SW-based atomic writes could be used always when the mounted bdev does
not support HW offload, but this strategy is not initially expected to be
used.
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250303171120.2837067-6-john.g.garry@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
show more ...
|
| b4de0e9b | 03-Mar-2025 |
John Garry <john.g.garry@oracle.com> |
iomap: Rename IOMAP_ATOMIC -> IOMAP_ATOMIC_HW
In future xfs will support a SW-based atomic write, so rename
IOMAP_ATOMIC -> IOMAP_ATOMIC_HW to be clear which mode is being used.
Also relocate setti
iomap: Rename IOMAP_ATOMIC -> IOMAP_ATOMIC_HW
In future xfs will support a SW-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.
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250303171120.2837067-3-john.g.garry@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
show more ...
|
| 034c29fb | 06-Feb-2025 |
Christoph Hellwig <hch@lst.de> |
iomap: add a IOMAP_F_ANON_WRITE flag
Add a IOMAP_F_ANON_WRITE flag that indicates that the write I/O does not
have a target block assigned to it yet at iomap time and the file system
will do that in
iomap: add a IOMAP_F_ANON_WRITE flag
Add a IOMAP_F_ANON_WRITE flag that indicates that the write I/O does not
have a target block assigned to it yet at iomap time and the file system
will do that in the bio submission handler, splitting the I/O as needed.
This is used to implement Zone Append based I/O for zoned XFS, where
splitting writes to the hardware limits and assigning a zone to them
happens just before sending the I/O off to the block layer, but could
also be useful for other things like compressed I/O.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-4-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
show more ...
|