ext4: avoid trim error on fs with small groups

[ Upstream commit 173b6e383d2a204c9921ffc1eca3b87aa2106c33 ]

A user reported FITRIM ioctl failing for him on ext4 on some devices
without apparent reason.  After some debugging we've found out that
these devices (being LVM volumes) report rather large discard
granularity of 42MB and the filesystem had 1k blocksize and thus group
size of 8MB. Because ext4 FITRIM implementation puts discard
granularity into minlen, ext4_trim_fs() declared the trim request as
invalid. However just silently doing nothing seems to be a more
appropriate reaction to such combination of parameters since user did
not specify anything wrong.

CC: Lukas Czerner <lczerner@redhat.com>
Fixes: 5c2ed62fd447 ("ext4: Adjust minlen with discard_granularity in the FITRIM ioctl")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211112152202.26614-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index cb54ea6461fd87a8950986924a296752b7cd01ee..413bf3d2f784437945dec5e36ad9649feda031da 100644 (file)
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1123,8 +1123,6 @@ resizefs_out:
                    sizeof(range)))
                        return -EFAULT;
 
-               range.minlen = max((unsigned int)range.minlen,
-                                  q->limits.discard_granularity);
                ret = ext4_trim_fs(sb, &range);
                if (ret < 0)
                        return ret;

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d7cb7d719ee5845924146bd92c5837b4042de266..60aef7fdd61d0fb22034ba8f7dfbe6280fc13433 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5815,6 +5815,7 @@ out:
  */
 int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
 {
+       struct request_queue *q = bdev_get_queue(sb->s_bdev);
        struct ext4_group_info *grp;
        ext4_group_t group, first_group, last_group;
        ext4_grpblk_t cnt = 0, first_cluster, last_cluster;
@@ -5833,6 +5834,13 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
            start >= max_blks ||
            range->len < sb->s_blocksize)
                return -EINVAL;
+       /* No point to try to trim less than discard granularity */
+       if (range->minlen < q->limits.discard_granularity) {
+               minlen = EXT4_NUM_B2C(EXT4_SB(sb),
+                       q->limits.discard_granularity >> sb->s_blocksize_bits);
+               if (minlen > EXT4_CLUSTERS_PER_GROUP(sb))
+                       goto out;
+       }
        if (end >= max_blks)
                end = max_blks - 1;
        if (end <= first_data_blk)