diff mbox series

[v2] ext4: fix inconsistent between segment fstrim and full fstrim

Message ID 20231216010919.1995851-1-yebin10@huawei.com
State New
Headers
Series [v2] ext4: fix inconsistent between segment fstrim and full fstrim |

Commit Message

Ye Bin Dec. 16, 2023, 1:09 a.m. UTC 
  Suppose we issue two FITRIM ioctls for ranges [0,15] and [16,31] with
mininum length of trimmed range set to 8 blocks. If we have say a range of
blocks 10-22 free, this range will not be trimmed because it straddles the
boundary of the two FITRIM ranges and neither part is big enough. This is a
bit surprising to some users that call FITRIM on smaller ranges of blocks
to limit impact on the system. Also XFS trims all free space extents that
overlap with the specified range so we are inconsistent among filesystems.
Let's change ext4_try_to_trim_range() to consider for trimming the whole
free space extent that straddles the end of specified range, not just the
part of it within the range.

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/mballoc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

Comments

Theodore Ts'o Jan. 9, 2024, 2:53 a.m. UTC | #1 
On Sat, 16 Dec 2023 09:09:19 +0800, Ye Bin wrote:
> Suppose we issue two FITRIM ioctls for ranges [0,15] and [16,31] with
> mininum length of trimmed range set to 8 blocks. If we have say a range of
> blocks 10-22 free, this range will not be trimmed because it straddles the
> boundary of the two FITRIM ranges and neither part is big enough. This is a
> bit surprising to some users that call FITRIM on smaller ranges of blocks
> to limit impact on the system. Also XFS trims all free space extents that
> overlap with the specified range so we are inconsistent among filesystems.
> Let's change ext4_try_to_trim_range() to consider for trimming the whole
> free space extent that straddles the end of specified range, not just the
> part of it within the range.
> 
> [...]

Applied, thanks!

[1/1] ext4: fix inconsistent between segment fstrim and full fstrim
      commit: 3d1aa1169c45aba9d589be1eb4b131f26f0a663c

Best regards,
diff mbox series

Patch

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d72b5e3c92ec..d195461123d8 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -6753,13 +6753,15 @@  static int ext4_try_to_trim_range(struct super_block *sb,
 __acquires(ext4_group_lock_ptr(sb, e4b->bd_group))
 __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 {
-	ext4_grpblk_t next, count, free_count;
+	ext4_grpblk_t next, count, free_count, last, origin_start;
 	bool set_trimmed = false;
 	void *bitmap;
 
+	last = ext4_last_grp_cluster(sb, e4b->bd_group);
 	bitmap = e4b->bd_bitmap;
-	if (start == 0 && max >= ext4_last_grp_cluster(sb, e4b->bd_group))
+	if (start == 0 && max >= last)
 		set_trimmed = true;
+	origin_start = start;
 	start = max(e4b->bd_info->bb_first_free, start);
 	count = 0;
 	free_count = 0;
@@ -6768,7 +6770,10 @@  __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 		start = mb_find_next_zero_bit(bitmap, max + 1, start);
 		if (start > max)
 			break;
-		next = mb_find_next_bit(bitmap, max + 1, start);
+
+		next = mb_find_next_bit(bitmap, last + 1, start);
+		if (origin_start == 0 && next >= last)
+			set_trimmed = true;
 
 		if ((next - start) >= minblocks) {
 			int ret = ext4_trim_extent(sb, start, next - start, e4b);