[v4,08/27] btrfs: disable fallocate in HMZONED mode
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Message ID 20190823101036.796932-9-naohiro.aota@wdc.com
State New
Headers show
Series
  • btrfs zoned block device support
Related show

Commit Message

Naohiro Aota Aug. 23, 2019, 10:10 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 HMZONED mode for now.

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

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/file.c | 4 ++++
 1 file changed, 4 insertions(+)

Patch
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diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 58a18ed11546..7474010a997d 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3023,6 +3023,10 @@  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 HMZONED mode */
+	if (btrfs_fs_incompat(btrfs_sb(inode->i_sb), HMZONED))
+		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))