| Message ID | 1503751772-158812-1-git-send-email-yunlong.song@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2017/8/26 20:49, Yunlong Song wrote: > 1. write file A with 5 blocks to current empty active segment > 2. remove file A > 3. write checkpoint > 4. write file B with 507 blocks to the same active segment > > If file B is alive all the time, the blocks used by file A will never be > discarded. So current active segment should also be treated as a candidate > for small discards. I don't think that would be a big issue, since there will not be any freezing log headers, once log header moves, later invalid blocks could be discarded. Thanks, > > Signed-off-by: Yunlong Song <yunlong.song@huawei.com> > --- > fs/f2fs/segment.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 8375257..a2e7c8f 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, > return false; > > if (!force) { > - if (!test_opt(sbi, DISCARD) || !se->valid_blocks || > + if (!test_opt(sbi, DISCARD) || > + (!se->valid_blocks && > + !IS_CURSEG(sbi, cpc->trim_start)) || > SM_I(sbi)->dcc_info->nr_discards >= > SM_I(sbi)->dcc_info->max_discards) > return false; >
How? Can the invalid blocks of file A be discarded, if file B is alive all the time and fggc_threshold is 507 ? On 2017/8/28 17:59, Chao Yu wrote: > On 2017/8/26 20:49, Yunlong Song wrote: >> 1. write file A with 5 blocks to current empty active segment >> 2. remove file A >> 3. write checkpoint >> 4. write file B with 507 blocks to the same active segment >> >> If file B is alive all the time, the blocks used by file A will never be >> discarded. So current active segment should also be treated as a candidate >> for small discards. > I don't think that would be a big issue, since there will not be any freezing > log headers, once log header moves, later invalid blocks could be discarded. > > Thanks, > >> Signed-off-by: Yunlong Song <yunlong.song@huawei.com> >> --- >> fs/f2fs/segment.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index 8375257..a2e7c8f 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, >> return false; >> >> if (!force) { >> - if (!test_opt(sbi, DISCARD) || !se->valid_blocks || >> + if (!test_opt(sbi, DISCARD) || >> + (!se->valid_blocks && >> + !IS_CURSEG(sbi, cpc->trim_start)) || >> SM_I(sbi)->dcc_info->nr_discards >= >> SM_I(sbi)->dcc_info->max_discards) >> return false; >> > > . >
On 2017/8/28 21:21, Yunlong Song wrote: > How? Can the invalid blocks of file A be discarded, if file B is alive > all the time and fggc_threshold is 507 ? As I traced, with small discard, we scan discard candidates from all dirty segments which also include current segment, so seems we don't need to wait log header moving on. Thanks, > > On 2017/8/28 17:59, Chao Yu wrote: >> On 2017/8/26 20:49, Yunlong Song wrote: >>> 1. write file A with 5 blocks to current empty active segment >>> 2. remove file A >>> 3. write checkpoint >>> 4. write file B with 507 blocks to the same active segment >>> >>> If file B is alive all the time, the blocks used by file A will never be >>> discarded. So current active segment should also be treated as a candidate >>> for small discards. >> I don't think that would be a big issue, since there will not be any freezing >> log headers, once log header moves, later invalid blocks could be discarded. >> >> Thanks, >> >>> Signed-off-by: Yunlong Song <yunlong.song@huawei.com> >>> --- >>> fs/f2fs/segment.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >>> index 8375257..a2e7c8f 100644 >>> --- a/fs/f2fs/segment.c >>> +++ b/fs/f2fs/segment.c >>> @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, >>> return false; >>> >>> if (!force) { >>> - if (!test_opt(sbi, DISCARD) || !se->valid_blocks || >>> + if (!test_opt(sbi, DISCARD) || >>> + (!se->valid_blocks && >>> + !IS_CURSEG(sbi, cpc->trim_start)) || >>> SM_I(sbi)->dcc_info->nr_discards >= >>> SM_I(sbi)->dcc_info->max_discards) >>> return false; >>> >> >> . >> >
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 8375257..a2e7c8f 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, return false; if (!force) { - if (!test_opt(sbi, DISCARD) || !se->valid_blocks || + if (!test_opt(sbi, DISCARD) || + (!se->valid_blocks && + !IS_CURSEG(sbi, cpc->trim_start)) || SM_I(sbi)->dcc_info->nr_discards >= SM_I(sbi)->dcc_info->max_discards) return false;
1. write file A with 5 blocks to current empty active segment 2. remove file A 3. write checkpoint 4. write file B with 507 blocks to the same active segment If file B is alive all the time, the blocks used by file A will never be discarded. So current active segment should also be treated as a candidate for small discards. Signed-off-by: Yunlong Song <yunlong.song@huawei.com> --- fs/f2fs/segment.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)