2022-04-18 03:57:08

by Dmitry Monakhov

Subject: [PATCH] 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

Signed-off-by: Dmitry Monakhov <[email protected]>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 252c168454c7..c7332eb65ccd 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -6407,7 +6407,7 @@ __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 may_cache)
{
struct ext4_buddy e4b;
int ret;
@@ -6426,7 +6426,7 @@ 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 && may_cache)
EXT4_MB_GRP_SET_TRIMMED(e4b.bd_info);
} else {
ret = 0;
@@ -6463,6 +6463,7 @@ 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;
@@ -6481,8 +6482,10 @@ 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)
@@ -6496,6 +6499,7 @@ 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);
@@ -6512,12 +6516,13 @@ 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;
--
2.7.4

2022-05-14 04:28:54

by Theodore Ts'o

Subject: Re: [PATCH] ext4: mark group as trimmed only if it was fully scanned

On Sun, 17 Apr 2022 20:03:15 +0300, Dmitry Monakhov wrote:
> 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
>
> [...]

Applied, thanks!

[1/1] ext4: mark group as trimmed only if it was fully scanned
commit: 326118d762e2eaaec580fcc151f853a96f3ad71a

Best regards,
--
Theodore Ts'o <[email protected]>