[PATCH 5.17 636/772] ext4: mark group as trimmed only if it was fully scanned

Greg Kroah-Hartman
2022-06-07T21:39:21Z

From: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>

commit d63c00ea435a5352f486c259665a4ced60399421 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/mballoc.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -6377,6 +6377,7 @@ __releases(ext4_group_lock_ptr(sb, e4b->
* @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
@@ -6386,7 +6387,7 @@ __releases(ext4_group_lock_ptr(sb, e4b->
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;
@@ -6405,7 +6406,7 @@ ext4_trim_all_free(struct super_block *s
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;
@@ -6442,6 +6443,7 @@ int ext4_trim_fs(struct super_block *sb,
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;
@@ -6460,8 +6462,10 @@ int ext4_trim_fs(struct super_block *sb,
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)
@@ -6475,6 +6479,7 @@ int ext4_trim_fs(struct super_block *sb,

/* 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);
@@ -6491,12 +6496,13 @@ int ext4_trim_fs(struct super_block *sb,
* 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;