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f2fs: Fix indefinite loop in f2fs_gc()

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Policy - Foreground GC, LFS and greedy GC mode.

Under this policy, f2fs_gc() loops forever to GC as it doesn't have
enough free segements to proceed and thus it keeps calling gc_more
for the same victim segment.  This can happen if the selected victim
segment could not be GC'd due to failed blkaddr validity check i.e.
is_alive() returns false for the blocks set in current validity map.

Fix this by keeping track of such invalid segments and skip those
segments for selection in get_victim_by_default() to avoid endless
GC loop under such error scenarios. Currently, add this logic under
CONFIG_F2FS_CHECK_FS to be able to root cause the issue in debug
version.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: fix wrong bitmap size]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Sahitya Tummala
2019-08-07 19:10:32 +05:30
committed by Jaegeuk Kim
parent 2fde3dd14e
commit bbf9f7d90f
3 changed files with 46 additions and 9 deletions
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25
fs/f2fs/gc.c
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@@ -382,6 +382,16 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
nsearched++;
}
#ifdef CONFIG_F2FS_CHECK_FS
/*
* skip selecting the invalid segno (that is failed due to block
* validity check failure during GC) to avoid endless GC loop in
* such cases.
*/
if (test_bit(segno, sm->invalid_segmap))
goto next;
#endif
secno = GET_SEC_FROM_SEG(sbi, segno);
if (sec_usage_check(sbi, secno))
@@ -627,8 +637,21 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
source_blkaddr = datablock_addr(NULL, node_page, ofs_in_node);
f2fs_put_page(node_page, 1);
if (source_blkaddr != blkaddr)
if (source_blkaddr != blkaddr) {
#ifdef CONFIG_F2FS_CHECK_FS
unsigned int segno = GET_SEGNO(sbi, blkaddr);
unsigned long offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);
if (unlikely(check_valid_map(sbi, segno, offset))) {
if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {
f2fs_err(sbi, "mismatched blkaddr %u (source_blkaddr %u) in seg %u\n",
blkaddr, source_blkaddr, segno);
f2fs_bug_on(sbi, 1);
}
}
#endif
return false;
}
return true;
}