Commit f1569c4c authored Nov 10, 2020 by Naohiro Aota Committed by David Sterba Dec 09, 2020

btrfs: disable fallocate in ZONED mode



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 similar, so this
returns EOPNOTSUPP.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent d206e9c9

fs/btrfs/file.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -3308,6 +3308,10 @@ static long btrfs_fallocate(struct file *file, int mode,
		int blocksize = btrfs_inode_sectorsize(BTRFS_I(inode));
		int ret;

		/* Do not allow fallocate in ZONED mode */
		if (btrfs_is_zoned(btrfs_sb(inode->i_sb)))
		return -EOPNOTSUPP;

		alloc_start = round_down(offset, blocksize);
		alloc_end = round_up(offset + len, blocksize);
		cur_offset = alloc_start;

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