* [PATCH v12 2/2] xfs: add FALLOC_FL_WRITE_ZEROES to XFS code base
@ 2026-03-10 19:42 Lukas Herbolt
2026-03-10 20:52 ` Darrick J. Wong
2026-03-11 0:19 ` Dave Chinner
0 siblings, 2 replies; 3+ messages in thread
From: Lukas Herbolt @ 2026-03-10 19:42 UTC (permalink / raw)
To: linux-xfs; +Cc: cem, hch, djwong, pankaj.raghav, Pankaj Raghav, Lukas Herbolt
Add support for FALLOC_FL_WRITE_ZEROES if the underlying device
enable the unmap write zeroes operation.
Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Lukas Herbolt <lukas@herbolt.com>
---
v12 changes:
split from xfs_falloc_zero_range() into separate function
fs/xfs/xfs_file.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index fd049a1fc9c6..ede7be05d83e 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1318,6 +1318,49 @@ xfs_falloc_zero_range(
return xfs_falloc_setsize(file, new_size);
}
+static int
+xfs_falloc_write_zero_range(
+ struct file *file,
+ int mode,
+ loff_t offset,
+ loff_t len,
+ struct xfs_zone_alloc_ctx *ac)
+{
+ struct inode *inode = file_inode(file);
+ struct xfs_inode *ip = XFS_I(inode);
+ unsigned int blksize = i_blocksize(inode);
+ loff_t new_size = 0;
+ int error;
+
+ if (xfs_is_always_cow_inode(ip) ||
+ !bdev_write_zeroes_unmap_sectors(
+ xfs_inode_buftarg(ip)->bt_bdev))
+ return -EOPNOTSUPP;
+
+ trace_xfs_zero_file_space(ip);
+
+ error = xfs_falloc_newsize(file, mode, offset, len, &new_size);
+ if (error)
+ return error;
+
+ error = xfs_free_file_space(ip, offset, len, ac);
+ if (error)
+ return error;
+
+ len = round_up(offset + len, blksize) - round_down(offset, blksize);
+ offset = round_down(offset, blksize);
+ error = xfs_alloc_file_space(ip, offset, len, XFS_BMAPI_PREALLOC);
+ if (error)
+ return error;
+
+ error = xfs_falloc_setsize(file, new_size);
+ if (error)
+ return error;
+
+ return xfs_alloc_file_space(ip, offset, len,
+ XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO);
+}
+
static int
xfs_falloc_unshare_range(
struct file *file,
@@ -1377,7 +1420,7 @@ xfs_falloc_allocate_range(
(FALLOC_FL_ALLOCATE_RANGE | FALLOC_FL_KEEP_SIZE | \
FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE | \
FALLOC_FL_ZERO_RANGE | FALLOC_FL_INSERT_RANGE | \
- FALLOC_FL_UNSHARE_RANGE)
+ FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_WRITE_ZEROES)
STATIC long
__xfs_file_fallocate(
@@ -1423,6 +1466,10 @@ __xfs_file_fallocate(
case FALLOC_FL_ZERO_RANGE:
error = xfs_falloc_zero_range(file, mode, offset, len, ac);
break;
+ case FALLOC_FL_WRITE_ZEROES:
+ error = xfs_falloc_write_zero_range(file, mode, offset,
+ len, ac);
+ break;
case FALLOC_FL_UNSHARE_RANGE:
error = xfs_falloc_unshare_range(file, mode, offset, len);
break;
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH v12 2/2] xfs: add FALLOC_FL_WRITE_ZEROES to XFS code base
2026-03-10 19:42 [PATCH v12 2/2] xfs: add FALLOC_FL_WRITE_ZEROES to XFS code base Lukas Herbolt
@ 2026-03-10 20:52 ` Darrick J. Wong
2026-03-11 0:19 ` Dave Chinner
1 sibling, 0 replies; 3+ messages in thread
From: Darrick J. Wong @ 2026-03-10 20:52 UTC (permalink / raw)
To: Lukas Herbolt; +Cc: linux-xfs, cem, hch, pankaj.raghav, Pankaj Raghav
On Tue, Mar 10, 2026 at 08:42:46PM +0100, Lukas Herbolt wrote:
> Add support for FALLOC_FL_WRITE_ZEROES if the underlying device
> enable the unmap write zeroes operation.
>
> Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> Signed-off-by: Lukas Herbolt <lukas@herbolt.com>
> ---
> v12 changes:
> split from xfs_falloc_zero_range() into separate function
> fs/xfs/xfs_file.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index fd049a1fc9c6..ede7be05d83e 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1318,6 +1318,49 @@ xfs_falloc_zero_range(
> return xfs_falloc_setsize(file, new_size);
> }
>
> +static int
> +xfs_falloc_write_zero_range(
> + struct file *file,
> + int mode,
> + loff_t offset,
> + loff_t len,
> + struct xfs_zone_alloc_ctx *ac)
> +{
> + struct inode *inode = file_inode(file);
> + struct xfs_inode *ip = XFS_I(inode);
> + unsigned int blksize = i_blocksize(inode);
> + loff_t new_size = 0;
> + int error;
> +
> + if (xfs_is_always_cow_inode(ip) ||
> + !bdev_write_zeroes_unmap_sectors(
> + xfs_inode_buftarg(ip)->bt_bdev))
> + return -EOPNOTSUPP;
> +
> + trace_xfs_zero_file_space(ip);
I think we want to have a separate tracepoint for write-zeroes, but TBH
the fallocate tracepoints all kinda suck in that we don't record the
range or any of the flags so... there's a minor cleanup to be done
separately.
In the meantime this looks ok provided it doesn't break fsx/fsstress?
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
--D
> +
> + error = xfs_falloc_newsize(file, mode, offset, len, &new_size);
> + if (error)
> + return error;
> +
> + error = xfs_free_file_space(ip, offset, len, ac);
> + if (error)
> + return error;
> +
> + len = round_up(offset + len, blksize) - round_down(offset, blksize);
> + offset = round_down(offset, blksize);
> + error = xfs_alloc_file_space(ip, offset, len, XFS_BMAPI_PREALLOC);
> + if (error)
> + return error;
> +
> + error = xfs_falloc_setsize(file, new_size);
> + if (error)
> + return error;
> +
> + return xfs_alloc_file_space(ip, offset, len,
> + XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO);
> +}
> +
> static int
> xfs_falloc_unshare_range(
> struct file *file,
> @@ -1377,7 +1420,7 @@ xfs_falloc_allocate_range(
> (FALLOC_FL_ALLOCATE_RANGE | FALLOC_FL_KEEP_SIZE | \
> FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE | \
> FALLOC_FL_ZERO_RANGE | FALLOC_FL_INSERT_RANGE | \
> - FALLOC_FL_UNSHARE_RANGE)
> + FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_WRITE_ZEROES)
>
> STATIC long
> __xfs_file_fallocate(
> @@ -1423,6 +1466,10 @@ __xfs_file_fallocate(
> case FALLOC_FL_ZERO_RANGE:
> error = xfs_falloc_zero_range(file, mode, offset, len, ac);
> break;
> + case FALLOC_FL_WRITE_ZEROES:
> + error = xfs_falloc_write_zero_range(file, mode, offset,
> + len, ac);
> + break;
> case FALLOC_FL_UNSHARE_RANGE:
> error = xfs_falloc_unshare_range(file, mode, offset, len);
> break;
> --
> 2.53.0
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v12 2/2] xfs: add FALLOC_FL_WRITE_ZEROES to XFS code base
2026-03-10 19:42 [PATCH v12 2/2] xfs: add FALLOC_FL_WRITE_ZEROES to XFS code base Lukas Herbolt
2026-03-10 20:52 ` Darrick J. Wong
@ 2026-03-11 0:19 ` Dave Chinner
1 sibling, 0 replies; 3+ messages in thread
From: Dave Chinner @ 2026-03-11 0:19 UTC (permalink / raw)
To: Lukas Herbolt; +Cc: linux-xfs, cem, hch, djwong, pankaj.raghav, Pankaj Raghav
On Tue, Mar 10, 2026 at 08:42:46PM +0100, Lukas Herbolt wrote:
> Add support for FALLOC_FL_WRITE_ZEROES if the underlying device
> enable the unmap write zeroes operation.
>
> Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> Signed-off-by: Lukas Herbolt <lukas@herbolt.com>
> ---
> v12 changes:
> split from xfs_falloc_zero_range() into separate function
> fs/xfs/xfs_file.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 48 insertions(+), 1 deletion(-)
Ugh, I just reviewed v11 and pointed out how unnecessarily complex
this new "three phase" method is. Please given people a chance to
review the code by waiting a couple of days before posting a new
version....
My comments against v11 are still relevant; working around low level
truncate issues when calling truncate to transactionally update the
file size is not necessary is less than ideal.
-Dave.
--
Dave Chinner
dgc@kernel.org
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-03-10 19:42 [PATCH v12 2/2] xfs: add FALLOC_FL_WRITE_ZEROES to XFS code base Lukas Herbolt
2026-03-10 20:52 ` Darrick J. Wong
2026-03-11 0:19 ` Dave Chinner
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