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| author | Ojaswin Mujoo <ojaswin@linux.ibm.com> | 2023-05-30 14:33:47 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2023-06-27 01:34:56 +0200 |
| commit | 4f3d1e4533b0982034f316ace85415d3bc57e3da (patch) | |
| tree | e8d560cac382cfb9025631d9c81fa72494fb8a9a | |
| parent | ext4: Don't skip prefetching BLOCK_UNINIT groups (diff) | |
| download | linux-4f3d1e4533b0982034f316ace85415d3bc57e3da.tar.xz linux-4f3d1e4533b0982034f316ace85415d3bc57e3da.zip | |
ext4: Ensure ext4_mb_prefetch_fini() is called for all prefetched BGs
Before this patch, the call stack in ext4_run_li_request is as follows:
/*
* nr = no. of BGs we want to fetch (=s_mb_prefetch)
* prefetch_ios = no. of BGs not uptodate after
* ext4_read_block_bitmap_nowait()
*/
next_group = ext4_mb_prefetch(sb, group, nr, prefetch_ios);
ext4_mb_prefetch_fini(sb, next_group prefetch_ios);
ext4_mb_prefetch_fini() will only try to initialize buddies for BGs in
range [next_group - prefetch_ios, next_group). This is incorrect since
sometimes (prefetch_ios < nr), which causes ext4_mb_prefetch_fini() to
incorrectly ignore some of the BGs that might need initialization. This
issue is more notable now with the previous patch enabling "fetching" of
BLOCK_UNINIT BGs which are marked buffer_uptodate by default.
Fix this by passing nr to ext4_mb_prefetch_fini() instead of
prefetch_ios so that it considers the right range of groups.
Similarly, make sure we don't pass nr=0 to ext4_mb_prefetch_fini() in
ext4_mb_regular_allocator() since we might have prefetched BLOCK_UNINIT
groups that would need buddy initialization.
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/05e648ae04ec5b754207032823e9c1de9a54f87a.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/mballoc.c | 4 | ||||
| -rw-r--r-- | fs/ext4/super.c | 11 |
2 files changed, 4 insertions, 11 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index fb9780bb1b54..d2a0259107c2 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2734,8 +2734,6 @@ repeat: if ((prefetch_grp == group) && (cr > CR1 || prefetch_ios < sbi->s_mb_prefetch_limit)) { - unsigned int curr_ios = prefetch_ios; - nr = sbi->s_mb_prefetch; if (ext4_has_feature_flex_bg(sb)) { nr = 1 << sbi->s_log_groups_per_flex; @@ -2744,8 +2742,6 @@ repeat: } prefetch_grp = ext4_mb_prefetch(sb, group, nr, &prefetch_ios); - if (prefetch_ios == curr_ios) - nr = 0; } /* This now checks without needing the buddy page */ diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 39591fb78c1d..7f9b087b9b20 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3692,16 +3692,13 @@ static int ext4_run_li_request(struct ext4_li_request *elr) ext4_group_t group = elr->lr_next_group; unsigned int prefetch_ios = 0; int ret = 0; + int nr = EXT4_SB(sb)->s_mb_prefetch; u64 start_time; if (elr->lr_mode == EXT4_LI_MODE_PREFETCH_BBITMAP) { - elr->lr_next_group = ext4_mb_prefetch(sb, group, - EXT4_SB(sb)->s_mb_prefetch, &prefetch_ios); - if (prefetch_ios) - ext4_mb_prefetch_fini(sb, elr->lr_next_group, - prefetch_ios); - trace_ext4_prefetch_bitmaps(sb, group, elr->lr_next_group, - prefetch_ios); + elr->lr_next_group = ext4_mb_prefetch(sb, group, nr, &prefetch_ios); + ext4_mb_prefetch_fini(sb, elr->lr_next_group, nr); + trace_ext4_prefetch_bitmaps(sb, group, elr->lr_next_group, nr); if (group >= elr->lr_next_group) { ret = 1; if (elr->lr_first_not_zeroed != ngroups && |