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f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc

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The f2fs_gc() called by f2fs_balance_fs() requires to be called outside of
fi->i_gc_rwsem[WRITE], since f2fs_gc() can try to grab it in a loop.

If it hits the miximum retrials in GC, let's give a chance to release
gc_mutex for a short time in order not to go into live lock in the worst
case.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim
2018-07-25 12:11:56 +09:00
parent 853137cef4
commit 6f8d445506
6 changed files with 92 additions and 68 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
fs/f2fs/gc.c
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@@ -882,6 +882,7 @@ next_step:
if (!down_write_trylock(
&F2FS_I(inode)->i_gc_rwsem[WRITE])) {
iput(inode);
sbi->skipped_gc_rwsem++;
continue;
}
@@ -911,6 +912,7 @@ next_step:
continue;
if (!down_write_trylock(
&fi->i_gc_rwsem[WRITE])) {
sbi->skipped_gc_rwsem++;
up_write(&fi->i_gc_rwsem[READ]);
continue;
}
@@ -1048,6 +1050,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
.iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
};
unsigned long long last_skipped = sbi->skipped_atomic_files[FG_GC];
unsigned long long first_skipped;
unsigned int skipped_round = 0, round = 0;
trace_f2fs_gc_begin(sbi->sb, sync, background,
@@ -1060,6 +1063,8 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
prefree_segments(sbi));
cpc.reason = __get_cp_reason(sbi);
sbi->skipped_gc_rwsem = 0;
first_skipped = last_skipped;
gc_more:
if (unlikely(!(sbi->sb->s_flags & SB_ACTIVE))) {
ret = -EINVAL;
@@ -1101,7 +1106,8 @@ gc_more:
total_freed += seg_freed;
if (gc_type == FG_GC) {
if (sbi->skipped_atomic_files[FG_GC] > last_skipped)
if (sbi->skipped_atomic_files[FG_GC] > last_skipped ||
sbi->skipped_gc_rwsem)
skipped_round++;
last_skipped = sbi->skipped_atomic_files[FG_GC];
round++;
@@ -1110,15 +1116,23 @@ gc_more:
if (gc_type == FG_GC)
sbi->cur_victim_sec = NULL_SEGNO;
if (!sync) {
if (has_not_enough_free_secs(sbi, sec_freed, 0)) {
if (skipped_round > MAX_SKIP_ATOMIC_COUNT &&
skipped_round * 2 >= round)
f2fs_drop_inmem_pages_all(sbi, true);
if (sync)
goto stop;
if (has_not_enough_free_secs(sbi, sec_freed, 0)) {
if (skipped_round <= MAX_SKIP_GC_COUNT ||
skipped_round * 2 < round) {
segno = NULL_SEGNO;
goto gc_more;
}
if (first_skipped < last_skipped &&
(last_skipped - first_skipped) >
sbi->skipped_gc_rwsem) {
f2fs_drop_inmem_pages_all(sbi, true);
segno = NULL_SEGNO;
goto gc_more;
}
if (gc_type == FG_GC)
ret = f2fs_write_checkpoint(sbi, &cpc);
}