diff mbox series

[v10,09/41] btrfs: disable fallocate in ZONED mode

Message ID 5136fb8ba2a9746bfc55247c93b86e33bdd7eb7b.1605007036.git.naohiro.aota@wdc.com (mailing list archive)
State New, archived
Headers show
Series btrfs: zoned block device support | expand

Commit Message

Naohiro Aota Nov. 10, 2020, 11:26 a.m. UTC 
fallocate() is implemented by reserving actual extent instead of
reservations. This can result in exposing the sequential write constraint
of host-managed zoned block devices to the application, which would break
the POSIX semantic for the fallocated file.  To avoid this, report
fallocate() as not supported when in ZONED mode for now.

In the future, we may be able to implement "in-memory" fallocate() in ZONED
mode by utilizing space_info->bytes_may_use or so.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/file.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Anand Jain Nov. 20, 2020, 4:28 a.m. UTC | #1 
On 10/11/20 7:26 pm, Naohiro Aota wrote:
> fallocate() is implemented by reserving actual extent instead of
> reservations. This can result in exposing the sequential write constraint
> of host-managed zoned block devices to the application, which would break
> the POSIX semantic for the fallocated file.  To avoid this, report
> fallocate() as not supported when in ZONED mode for now.
> 
> In the future, we may be able to implement "in-memory" fallocate() in ZONED
> mode by utilizing space_info->bytes_may_use or so.
> 
> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Looks good.

Reviewed-by: Anand Jain <anand.jain@orcle.com>

Thanks.
diff mbox series

Patch

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 0ff659455b1e..68938a43081e 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3341,6 +3341,10 @@  static long btrfs_fallocate(struct file *file, int mode,
 	alloc_end = round_up(offset + len, blocksize);
 	cur_offset = alloc_start;
 
+	/* Do not allow fallocate in ZONED mode */
+	if (btrfs_is_zoned(btrfs_sb(inode->i_sb)))
+		return -EOPNOTSUPP;
+
 	/* Make sure we aren't being give some crap mode */
 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
 		     FALLOC_FL_ZERO_RANGE))