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 75fff707beb6a63153f14678fe1d7b5eb6601b7c..e7384a6e6a083fa2bb03d5b013611aacd3af813f 100644 (file)
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -760,8 +760,6 @@ 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 807331da9dfc14345f2b992d96ef1ed6b5e9d7a9..2a7fb2cf19b81e0ce160442c8df4056f0af50098 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5224,6 +5224,7 @@ 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;
@@ -5242,6 +5243,13 @@ 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)