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Zhang Yi points out that the dynamic folio_batch allocation in
iomap_fill_dirty_folios() is problematic for the ext4 on iomap work
that is under development because it doesn't sufficiently handle the
allocation failure case (by allowing a retry, for example). We've
also seen lockdep (via syzbot) complain recently about the scope of
the allocation.
The dynamic allocation was initially added for simplicity and to
help indicate whether the batch was used or not by the calling fs.
To address these issues, put the batch on the stack of
iomap_zero_range() and use a flag to control whether the batch
should be used in the iomap folio lookup path. This keeps things
simple and eliminates allocation issues with lockdep and for ext4 on
iomap.
While here, also clean up the fill helper signature to be more
consistent with the underlying filemap helper. Pass through the
return value of the filemap helper (folio count) and update the
lookup offset via an out param.
Fixes: 395ed1ef0012 ("iomap: optional zero range dirty folio processing")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://patch.msgid.link/20251208140548.373411-1-bfoster@redhat.com
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Instead of requiring that the caller calls iomap_finish_folio_read()
even if the ->read_folio_range() callback returns an error, account for
this internally in iomap instead, which makes the interface simpler and
makes it match writeback's ->read_folio_range() error handling
expectations.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://patch.msgid.link/20251111193658.3495942-6-joannelkoong@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Pending writebacks must be accounted for to determine when all requests
have completed and writeback on the folio should be ended. Currently
this is done by atomically incrementing ifs->write_bytes_pending for
every range to be written back.
Instead, the number of atomic operations can be minimized by setting
ifs->write_bytes_pending to the folio size, internally tracking how many
bytes are written back asynchronously, and then after sending off all
the requests, decrementing ifs->write_bytes_pending by the number of
bytes not written back asynchronously. Now, for N ranges written back,
only N + 2 atomic operations are required instead of 2N + 2.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://patch.msgid.link/20251111193658.3495942-5-joannelkoong@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Document that iomap_finish_folio_write() must be called after writeback
on the range completes.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://patch.msgid.link/20251111193658.3495942-4-joannelkoong@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Btrfs requires all of its bios to be fs block aligned, normally it's
totally fine but with the incoming block size larger than page size
(bs > ps) support, the requirement is no longer met for direct IOs.
Because iomap_dio_bio_iter() calls bio_iov_iter_get_pages(), only
requiring alignment to be bdev_logical_block_size().
In the real world that value is either 512 or 4K, on 4K page sized
systems it means bio_iov_iter_get_pages() can break the bio at any page
boundary, breaking btrfs' requirement for bs > ps cases.
To address this problem, introduce a new public iomap dio flag,
IOMAP_DIO_FSBLOCK_ALIGNED.
When calling __iomap_dio_rw() with that new flag, iomap_dio::flags will
inherit that new flag, and iomap_dio_bio_iter() will take fs block size
into the calculation of the alignment, and pass the alignment to
bio_iov_iter_get_pages(), respecting the fs block size requirement.
The initial user of this flag will be btrfs, which needs to calculate the
checksum for direct read and thus requires the biovec to be fs block
aligned for the incoming bs > ps support.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
[hch: also align pos/len, incorporate the trace flags from Darrick]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251031131045.1613229-2-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The only way zero range can currently process unwritten mappings
with dirty pagecache is to check whether the range is dirty before
mapping lookup and then flush when at least one underlying mapping
is unwritten. This ordering is required to prevent iomap lookup from
racing with folio writeback and reclaim.
Since zero range can skip ranges of unwritten mappings that are
clean in cache, this operation can be improved by allowing the
filesystem to provide a set of dirty folios that require zeroing. In
turn, rather than flush or iterate file offsets, zero range can
iterate on folios in the batch and advance over clean or uncached
ranges in between.
Add a folio_batch in struct iomap and provide a helper for
filesystems to populate the batch at lookup time. Update the folio
lookup path to return the next folio in the batch, if provided, and
advance the iter if the folio starts beyond the current offset.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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No errors are propagated in iomap_read_folio(). Change
iomap_read_folio() to a void return to make this clearer to callers.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add caller-provided callbacks for read and readahead so that it can be
used generically, especially by filesystems that are not block-based.
In particular, this:
* Modifies the read and readahead interface to take in a
struct iomap_read_folio_ctx that is publicly defined as:
struct iomap_read_folio_ctx {
const struct iomap_read_ops *ops;
struct folio *cur_folio;
struct readahead_control *rac;
void *read_ctx;
};
where struct iomap_read_ops is defined as:
struct iomap_read_ops {
int (*read_folio_range)(const struct iomap_iter *iter,
struct iomap_read_folio_ctx *ctx,
size_t len);
void (*read_submit)(struct iomap_read_folio_ctx *ctx);
};
read_folio_range() reads in the folio range and is required by the
caller to provide. read_submit() is optional and is used for
submitting any pending read requests.
* Modifies existing filesystems that use iomap for read and readahead to
use the new API, through the new statically inlined helpers
iomap_bio_read_folio() and iomap_bio_readahead(). There is no change
in functionality for those filesystems.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Most callers of iomap_iter_advance() do not need the remaining length
returned. Get rid of the extra iomap_length() call that
iomap_iter_advance() does.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a read_folio_range() handler for buffered writes that filesystems
may pass in if they wish to provide a custom handler for synchronously
reading in the contents of a folio.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
[hch: renamed to read_folio_range, pass less arguments]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-14-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The iomap_folio_ops are only used for buffered writes, including the zero
and unshare variants. Rename them to iomap_write_ops to better describe
the usage, and pass them through the call chain like the other operation
specific methods instead of through the iomap.
xfs_iomap_valid grows a IOMAP_HOLE check to keep the existing behavior
that never attached the folio_ops to a iomap representing a hole.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-12-hch@lst.de
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Allow fuse to use iomap_writeback_folio for folio laundering. Note
that the caller needs to manually submit the pending writeback context.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-11-hch@lst.de
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a new iomap_start_folio_write helper to abstract away the
write_bytes_pending handling, and export it and the existing
iomap_finish_folio_write for non-iomap writeback in fuse.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-7-hch@lst.de
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Replace the ioend pointer in iomap_writeback_ctx with a void *wb_ctx
one to facilitate non-block, non-ioend writeback for use. Rename
the submit_ioend method to writeback_submit and make it mandatory so
that the generic writeback code stops seeing ioends and bios.
Co-developed-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-6-hch@lst.de
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Replace ->map_blocks with a new ->writeback_range, which differs in the
following ways:
- it must also queue up the I/O for writeback, that is called into the
slightly refactored and extended in scope iomap_add_to_ioend for
each region
- can handle only a part of the requested region, that is the retry
loop for partial mappings moves to the caller
- handles cleanup on failures as well, and thus also replaces the
discard_folio method only implemented by XFS.
This will allow to use the iomap writeback code also for file systems
that are not block based like fuse.
Co-developed-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-5-hch@lst.de
Acked-by: Damien Le Moal <dlemoal@kernel.org> # zonefs
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add inode and wpc fields to pass the inode and writeback context that
are needed in the entire writeback call chain, and let the callers
initialize all fields in the writeback context before calling
iomap_writepages to simplify the argument passing.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-3-hch@lst.de
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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DONTCACHE I/O must have the completion punted to a workqueue, just like
what is done for unwritten extents, as the completion needs task context
to perform the invalidation of the folio(s). However, if writeback is
started off filemap_fdatawrite_range() off generic_sync() and it's an
overwrite, then the DONTCACHE marking gets lost as iomap_add_to_ioend()
don't look at the folio being added and no further state is passed down
to help it know that this is a dropbehind/DONTCACHE write.
Check if the folio being added is marked as dropbehind, and set
IOMAP_IOEND_DONTCACHE if that is the case. Then XFS can factor this into
the decision making of completion context in xfs_submit_ioend().
Additionally include this ioend flag in the NOMERGE flags, to avoid
mixing it with unrelated IO.
Since this is the 3rd flag that will cause XFS to punt the completion to
a workqueue, add a helper so that each one of them can get appropriately
commented.
This fixes extra page cache being instantiated when the write performed
is an overwrite, rather than newly instantiated blocks.
Fixes: b2cd5ae693a3 ("iomap: make buffered writes work with RWF_DONTCACHE")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/5153f6e8-274d-4546-bf55-30a5018e0d03@kernel.dk
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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IOMAP_F_ATOMIC_BIO mistakenly took the same value as of IOMAP_F_SIZE_CHANGED
in patch '370a6de7651b ("iomap: rework IOMAP atomic flags")'.
Let's fix this and let's also create some more space for filesystem reported
flags to avoid this in future. This patch makes the core iomap flags to start
from bit 15, moving downwards. Note that "flags" member within struct iomap
is of type u16.
Fixes: 370a6de7651b ("iomap: rework IOMAP atomic flags")
Signed-off-by: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20250327170119.61045-1-ritesh.list@gmail.com
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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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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>
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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>
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gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Bring in iomap changes that xfs relies on.
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add iomap buffered write support for RWF_DONTCACHE. If RWF_DONTCACHE is
set for a write, mark the folios being written as uncached. Then
writeback completion will drop the pages. The write_iter handler simply
kicks off writeback for the pages, and writeback completion will take
care of the rest.
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20250204184047.356762-2-axboe@kernel.dk
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Various iomap_iter_advance() calls advance by the full mapping
length and thus have no need for the current length input or
post-advance remaining length output from the standard advance
function. Add an iomap_iter_advance_full() helper to clean up these
cases.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250224144757.237706-13-bfoster@redhat.com
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The iter.processed field name is no longer appropriate now that
iomap operations do not return the number of bytes processed. Rename
the field to iter.status to reflect that a success or error code is
expected.
Also change the type to int as there is no longer a need for an s64.
This reduces the size of iomap_iter by 8 bytes due to a combination
of smaller type and reduction in structure padding. While here, fix
up the return types of various _iter() helpers to reflect the type
change.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250224144757.237706-12-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The current iomap_iter iteration model reads the mapping from the
filesystem, processes the subrange of the operation associated with
the current mapping, and returns the number of bytes processed back
to the iteration code. The latter advances the position and
remaining length of the iter in preparation for the next iteration.
At the _iter() handler level, this tends to produce a processing
loop where the local code pulls the current position and remaining
length out of the iter, iterates it locally based on file offset,
and then breaks out when the associated range has been fully
processed.
This works well enough for current handlers, but upcoming
enhancements require a bit more flexibility in certain situations.
Enhancements for zero range will lead to a situation where the
processing loop is no longer a pure ascending offset walk, but
rather dictated by pagecache state and folio lookup. Since folio
lookup and write preparation occur at different levels, it is more
difficult to manage position and length outside of the iter.
To provide more flexibility to certain iomap operations, introduce
support for incremental iomap_iter advances from within the
operation itself. This allows more granular advances for operations
that might not use the typical file offset based walk.
Note that the semantics for operations that use incremental advances
is slightly different than traditional operations. Operations that
advance the iter directly are expected to return success or failure
(i.e. 0 or negative error code) in iter.processed rather than the
number of bytes processed.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-8-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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As a final step for generic iter advance, export the helper and
update it to return the remaining length of the current iteration
after the advance. This will usually be 0 in the iomap_iter() case,
but will be useful for the various operations that iterate on their
own and will be updated to advance as they progress.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-7-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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In preparation to support more granular iomap iter advancing, factor
the pos/len values as parameters to length calculation.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250207143253.314068-2-bfoster@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Allow the file system to pass private data which can be used by the
iomap_begin and iomap_end methods through the private pointer in the
iomap_iter structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-12-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Allow the file system to pass private data which can be used by the
iomap_begin and iomap_end methods through the private pointer in the
iomap_iter structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-11-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Allow the file system to pass private data which can be used by the
iomap_begin and iomap_end methods through the private pointer in the
iomap_iter structure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-10-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a private data field to struct iomap_ioend so that the file system
can attach information to it. Zoned XFS will use this for a pointer to
the open zone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-9-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
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struct iomap_ioend currently tracks outstanding buffered writes and has
some really nice code in core iomap and XFS to merge contiguous I/Os
an defer them to userspace for completion in a very efficient way.
For zoned writes we'll also need a per-bio user context completion to
record the written blocks, and the infrastructure for that would look
basically like the ioend handling for buffered I/O.
So instead of reinventing the wheel, reuse the existing infrastructure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-8-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Provide helpers for file systems to split bios in the direct I/O and
writeback I/O submission handlers. The split ioends are chained to
the parent ioend so that only the parent ioend originally generated
by the iomap layer will be processed after all the chained off children
have completed. This is based on the block layer bio chaining that has
supported a similar mechanism for a long time.
This Follows btrfs' lead and don't try to build bios to hardware limits
for zone append commands, but instead build them as normal unconstrained
bios and split them to the hardware limits in the I/O submission handler.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-5-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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>
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The ioend fields for distinct types of I/O are a bit complicated.
Consolidate them into a single io_flag field with it's own flags
decoupled from the iomap flags. This also prepares for adding a new
flag that is unrelated to both of the iomap namespaces.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-3-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Change ->prepare_ioend to ->submit_ioend and require file systems that
implement it to submit the bio. This is needed for file systems that
do their own work on the bios before submitting them to the block layer
like btrfs or zoned xfs. To make this easier also pass the writeback
context to the method.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250206064035.2323428-2-hch@lst.de
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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During concurrent append writes to XFS filesystem, zero padding data
may appear in the file after power failure. This happens due to imprecise
disk size updates when handling write completion.
Consider this scenario with concurrent append writes same file:
Thread 1: Thread 2:
------------ -----------
write [A, A+B]
update inode size to A+B
submit I/O [A, A+BS]
write [A+B, A+B+C]
update inode size to A+B+C
<I/O completes, updates disk size to min(A+B+C, A+BS)>
<power failure>
After reboot:
1) with A+B+C < A+BS, the file has zero padding in range [A+B, A+B+C]
|< Block Size (BS) >|
|DDDDDDDDDDDDDDDD0000000000000000|
^ ^ ^
A A+B A+B+C
(EOF)
2) with A+B+C > A+BS, the file has zero padding in range [A+B, A+BS]
|< Block Size (BS) >|< Block Size (BS) >|
|DDDDDDDDDDDDDDDD0000000000000000|00000000000000000000000000000000|
^ ^ ^ ^
A A+B A+BS A+B+C
(EOF)
D = Valid Data
0 = Zero Padding
The issue stems from disk size being set to min(io_offset + io_size,
inode->i_size) at I/O completion. Since io_offset+io_size is block
size granularity, it may exceed the actual valid file data size. In
the case of concurrent append writes, inode->i_size may be larger
than the actual range of valid file data written to disk, leading to
inaccurate disk size updates.
This patch modifies the meaning of io_size to represent the size of
valid data within EOF in an ioend. If the ioend spans beyond i_size,
io_size will be trimmed to provide the file with more accurate size
information. This is particularly useful for on-disk size updates
at completion time.
After this change, ioends that span i_size will not grow or merge with
other ioends in concurrent scenarios. However, these cases that need
growth/merging rarely occur and it seems no noticeable performance impact.
Although rounding up io_size could enable ioend growth/merging in these
scenarios, we decided to keep the code simple after discussion [1].
Another benefit is that it makes the xfs_ioend_is_append() check more
accurate, which can reduce unnecessary end bio callbacks of xfs_end_bio()
in certain scenarios, such as repeated writes at the file tail without
extending the file size.
Link [1]: https://patchwork.kernel.org/project/xfs/patch/20241113091907.56937-1-leo.lilong@huawei.com
Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure") # goes further back than this
Signed-off-by: Long Li <leo.lilong@huawei.com>
Link: https://lore.kernel.org/r/20241209114241.3725722-3-leo.lilong@huawei.com
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Pull xfs updates from Carlos Maiolino:
"The bulk of this pull request is a major rework that Darrick and
Christoph have been doing on XFS's real-time volume, coupled with a
few features to support this rework. It does also includes some bug
fixes.
- convert perag to use xarrays
- create a new generic allocation group structure
- add metadata inode dir trees
- create in-core rt allocation groups
- shard the RT section into allocation groups
- persist quota options with the enw metadata dir tree
- enable quota for RT volumes
- enable metadata directory trees
- some bugfixes"
* tag 'xfs-6.13-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (146 commits)
xfs: port ondisk structure checks from xfs/122 to the kernel
xfs: separate space btree structures in xfs_ondisk.h
xfs: convert struct typedefs in xfs_ondisk.h
xfs: enable metadata directory feature
xfs: enable realtime quota again
xfs: update sb field checks when metadir is turned on
xfs: reserve quota for realtime files correctly
xfs: create quota preallocation watermarks for realtime quota
xfs: report realtime block quota limits on realtime directories
xfs: persist quota flags with metadir
xfs: advertise realtime quota support in the xqm stat files
xfs: scrub quota file metapaths
xfs: fix chown with rt quota
xfs: use metadir for quota inodes
xfs: refactor xfs_qm_destroy_quotainos
xfs: use rtgroup busy extent list for FITRIM
xfs: implement busy extent tracking for rtgroups
xfs: port the perag discard code to handle generic groups
xfs: move the min and max group block numbers to xfs_group
xfs: adjust min_block usage in xfs_verify_agbno
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs untorn write support from Christian Brauner:
"An atomic write is a write issed with torn-write protection. This
means for a power failure or any hardware failure all or none of the
data from the write will be stored, never a mix of old and new data.
This work is already supported for block devices. If a block device is
opened with O_DIRECT and the block device supports atomic write, then
FMODE_CAN_ATOMIC_WRITE is added to the file of the opened block
device.
This contains the work to expand atomic write support to filesystems,
specifically ext4 and XFS. Currently, only support for writing exactly
one filesystem block atomically is added.
Since it's now possible to have filesystem block size > page size for
XFS, it's possible to write 4K+ blocks atomically on x86"
* tag 'vfs-6.13.untorn.writes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
iomap: drop an obsolete comment in iomap_dio_bio_iter
ext4: Do not fallback to buffered-io for DIO atomic write
ext4: Support setting FMODE_CAN_ATOMIC_WRITE
ext4: Check for atomic writes support in write iter
ext4: Add statx support for atomic writes
xfs: Support setting FMODE_CAN_ATOMIC_WRITE
xfs: Validate atomic writes
xfs: Support atomic write for statx
fs: iomap: Atomic write support
fs: Export generic_atomic_write_valid()
block: Add bdev atomic write limits helpers
fs/block: Check for IOCB_DIRECT in generic_atomic_write_valid()
block/fs: Pass an iocb to generic_atomic_write_valid()
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File systems might have boundaries over which merges aren't possible.
In fact these are very common, although most of the time some kind of
header at the beginning of this region (e.g. XFS alloation groups, ext4
block groups) automatically create a merge barrier. But if that is
not present, say for a device purely used for data we need to manually
communicate that to iomap.
Add a IOMAP_F_BOUNDARY flag to never merge I/O into a previous mapping.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Support direct I/O atomic writes by producing a single bio with REQ_ATOMIC
flag set.
Initially FSes (XFS) should only support writing a single FS block
atomically.
As with any atomic write, we should produce a single bio which covers the
complete write length.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
[djwong: clarify a couple of things in the docs]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull iomap fixes from Christian Brauner:
"Fixes for iomap to prevent data corruption bugs in the fallocate
unshare range implementation of fsdax and a small cleanup to turn
iomap_want_unshare_iter() into an inline function"
* tag 'vfs-6.12-rc6.iomap' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
iomap: turn iomap_want_unshare_iter into an inline function
fsdax: dax_unshare_iter needs to copy entire blocks
fsdax: remove zeroing code from dax_unshare_iter
iomap: share iomap_unshare_iter predicate code with fsdax
xfs: don't allocate COW extents when unsharing a hole
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iomap_want_unshare_iter currently sits in fs/iomap/buffered-io.c, which
depends on CONFIG_BLOCK. It is also in used in fs/dax.c whіch has no
such dependency. Given that it is a trivial check turn it into an inline
in include/linux/iomap.h to fix the DAX && !BLOCK build.
Fixes: 6ef6a0e821d3 ("iomap: share iomap_unshare_iter predicate code with fsdax")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241015041350.118403-1-hch@lst.de
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Currently iomap_file_buffered_write_punch_delalloc can be called from
XFS either with the invalidate lock held or not. To fix this while
keeping the locking in the file system and not the iomap library
code we'll need to life the locking up into the file system.
To prepare for that, open code iomap_file_buffered_write_punch_delalloc
in the only caller, and instead export iomap_write_delalloc_release.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Split out a pice of logic from iomap_file_buffered_write_punch_delalloc
that is useful for all iomap_end implementations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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The predicate code that iomap_unshare_iter uses to decide if it's really
needs to unshare a file range mapping should be shared with the fsdax
version, because right now they're opencoded and inconsistent.
Note that we simplify the predicate logic a bit -- we no longer allow
unsharing of inline data mappings, but there aren't any filesystems that
allow shared inline data currently.
This is a fix in the sense that it should have been ported to fsdax.
Fixes: b53fdb215d13 ("iomap: improve shared block detection in iomap_unshare_iter")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/172796813294.1131942.15762084021076932620.stgit@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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iomap_file_buffered_write_punch_delalloc can only return errors if either
the ->punch callback returned an error, or if someone changed the API of
mapping_seek_hole_data to return a negative error code that is not
-ENXIO.
As the only instance of ->punch never returns an error, an such an error
would be fatal anyway remove the entire error propagation and don't
return an error code from iomap_file_buffered_write_punch_delalloc.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-6-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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XFS will need to look at the flags in the iomap structure, so pass it
down all the way to the callback.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240910043949.3481298-5-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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