在 1/3/2025 11:26 AM, Chao Yu 写道: > On 2025/1/2 18:13, Chunhai Guo wrote: >> fstrim may miss candidates that need to be discarded in fstrim, as shown in >> the examples below. >> The root cause is that when cpc->reason is set with CP_DISCARD, >> add_discard_addrs() expects that ckpt_valid_map and cur_valid_map have been >> synced by seg_info_to_raw_sit() [1] and tries to find the candidates based >> on ckpt_valid_map and discard_map. However, seg_info_to_raw_sit() does not >> actually run before f2fs_exist_trim_candidates(), which results in failure. > Chunhai, > > Can you please use nodiscard option due to fstrim stopped to return > trimmed length after below commit: > > 5a6154920faf ("f2fs: don't issue discard commands in online discard is on")
Thank you for your explanation, but I guess this issue is not relevant to this commit, and I understand that '0 B (0 bytes) trimmed' is fine. The real problem is that there are actually many candidates that should be handled in fstrim, but it cannot find any of them. f2fs_trim_fs() f2fs_write_checkpoint() ... if (cpc->reason & CP_DISCARD) { if (!f2fs_exist_trim_candidates(sbi, cpc)) { unblock_operations(sbi); goto out; // Not candidate is found here and exit. } ... } >> root# cp testfile /f2fs_mountpoint >> >> root# f2fs_io fiemap 0 1 /f2fs_mountpoint/testfile >> Fiemap: offset = 0 len = 1 >> logical addr. physical addr. length flags >> 0 0000000000000000 0000000406a00000 000000003d800000 00001000 >> >> root# rm /f2fs_mountpoint/testfile >> >> root# fstrim -v -o 0x406a00000 -l 1024M /f2fs_mountpoint -- no candidate is >> found >> /f2fs_mountpoint: 0 B (0 bytes) trimmed >> >> [1] Please refer to commit d7bc2484b8d4 ("f2fs: fix small discards not to >> issue redundantly") for the relationship between seg_info_to_raw_sit() and >> add_discard_addrs(). >> >> Fixes: 25290fa5591d ("f2fs: return fs_trim if there is no candidate") >> Signed-off-by: Chunhai Guo <guochun...@vivo.com> >> --- >> fs/f2fs/segment.c | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index eade36c5ef13..8fe9f794b581 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -2070,7 +2070,7 @@ static int f2fs_issue_discard(struct f2fs_sb_info *sbi, >> } >> >> static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control >> *cpc, >> - bool check_only) >> + bool synced, bool check_only) >> { >> int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long); >> struct seg_entry *se = get_seg_entry(sbi, cpc->trim_start); >> @@ -2098,7 +2098,7 @@ static bool add_discard_addrs(struct f2fs_sb_info >> *sbi, struct cp_control *cpc, >> >> /* SIT_VBLOCK_MAP_SIZE should be multiple of sizeof(unsigned long) */ >> for (i = 0; i < entries; i++) >> - dmap[i] = force ? ~ckpt_map[i] & ~discard_map[i] : >> + dmap[i] = synced ? ~ckpt_map[i] & ~discard_map[i] : > I guess this condition "force ? ~ckpt_map[i] & ~discard_map[i]" didn't cover > all below cases, thoughts? > - ckpt_map[i] == 0 // write data, and then remove data before checkpoint > - ckpt_map[i] != 0 // remove data existed in previous checkpoint From the handling of ckpt_valid_map in update_sit_entry(), I guess the condition can cover both cases. For example, when the checkpoint is enabled, all the set bits in the ckpt_valid_map remain set before the checkpoint (even when the blocks are deleted), which makes it find all the right bits in both cases. Thanks, > > Thanks, > >> (cur_map[i] ^ ckpt_map[i]) & ckpt_map[i]; >> >> while (force || SM_I(sbi)->dcc_info->nr_discards <= >> @@ -3275,7 +3275,7 @@ bool f2fs_exist_trim_candidates(struct f2fs_sb_info >> *sbi, >> >> down_write(&SIT_I(sbi)->sentry_lock); >> for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++) { >> - if (add_discard_addrs(sbi, cpc, true)) { >> + if (add_discard_addrs(sbi, cpc, false, true)) { >> has_candidate = true; >> break; >> } >> @@ -4611,7 +4611,7 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, >> struct cp_control *cpc) >> /* add discard candidates */ >> if (!(cpc->reason & CP_DISCARD)) { >> cpc->trim_start = segno; >> - add_discard_addrs(sbi, cpc, false); >> + add_discard_addrs(sbi, cpc, false, false); >> } >> >> if (to_journal) { >> @@ -4653,7 +4653,7 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, >> struct cp_control *cpc) >> __u64 trim_start = cpc->trim_start; >> >> for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++) >> - add_discard_addrs(sbi, cpc, false); >> + add_discard_addrs(sbi, cpc, true, false); >> >> cpc->trim_start = trim_start; >> } _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel