ext4: mark group as trimmed only if it was fully scanned

Otherwise nonaligned fstrim calls will works inconveniently for iterative
scanners, for example:

// trim [0,16MB] for group-1, but mark full group as trimmed
fstrim  -o $((1024*1024*128)) -l $((1024*1024*16)) ./m
// handle [16MB,16MB] for group-1, do nothing because group already has the flag.
fstrim  -o $((1024*1024*144)) -l $((1024*1024*16)) ./m

[ Update function documentation for ext4_trim_all_free -- TYT ]

Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Link: https://lore.kernel.org/r/1650214995-860245-1-git-send-email-dmtrmonakhov@yandex-team.ru
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 3e715b837e702968b0187719c6c6e304b994f483..bc90635b757c070e5da92a3250409863606ba22b 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -6395,6 +6395,7 @@ __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
  * @start:             first group block to examine
  * @max:               last group block to examine
  * @minblocks:         minimum extent block count
+ * @set_trimmed:       set the trimmed flag if at least one block is trimmed
  *
  * ext4_trim_all_free walks through group's block bitmap searching for free
  * extents. When the free extent is found, mark it as used in group buddy
@@ -6404,7 +6405,7 @@ __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 static ext4_grpblk_t
 ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
                   ext4_grpblk_t start, ext4_grpblk_t max,
-                  ext4_grpblk_t minblocks)
+                  ext4_grpblk_t minblocks, bool set_trimmed)
 {
        struct ext4_buddy e4b;
        int ret;
@@ -6423,7 +6424,7 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
        if (!EXT4_MB_GRP_WAS_TRIMMED(e4b.bd_info) ||
            minblocks < EXT4_SB(sb)->s_last_trim_minblks) {
                ret = ext4_try_to_trim_range(sb, &e4b, start, max, minblocks);
-               if (ret >= 0)
+               if (ret >= 0 && set_trimmed)
                        EXT4_MB_GRP_SET_TRIMMED(e4b.bd_info);
        } else {
                ret = 0;
@@ -6460,6 +6461,7 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
        ext4_fsblk_t first_data_blk =
                        le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
        ext4_fsblk_t max_blks = ext4_blocks_count(EXT4_SB(sb)->s_es);
+       bool whole_group, eof = false;
        int ret = 0;
 
        start = range->start >> sb->s_blocksize_bits;
@@ -6478,8 +6480,10 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
                if (minlen > EXT4_CLUSTERS_PER_GROUP(sb))
                        goto out;
        }
-       if (end >= max_blks)
+       if (end >= max_blks - 1) {
                end = max_blks - 1;
+               eof = true;
+       }
        if (end <= first_data_blk)
                goto out;
        if (start < first_data_blk)
@@ -6493,6 +6497,7 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
 
        /* end now represents the last cluster to discard in this group */
        end = EXT4_CLUSTERS_PER_GROUP(sb) - 1;
+       whole_group = true;
 
        for (group = first_group; group <= last_group; group++) {
                grp = ext4_get_group_info(sb, group);
@@ -6509,12 +6514,13 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
                 * change it for the last group, note that last_cluster is
                 * already computed earlier by ext4_get_group_no_and_offset()
                 */
-               if (group == last_group)
+               if (group == last_group) {
                        end = last_cluster;
-
+                       whole_group = eof ? true : end == EXT4_CLUSTERS_PER_GROUP(sb) - 1;
+               }
                if (grp->bb_free >= minlen) {
                        cnt = ext4_trim_all_free(sb, group, first_cluster,
-                                               end, minlen);
+                                                end, minlen, whole_group);
                        if (cnt < 0) {
                                ret = cnt;
                                break;