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Date: Wed, 29 Mar 2017 15:04:30 +0800 From: heyunlei <heyunlei@...wei.com> To: Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <yuchao0@...wei.com> CC: <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <linux-f2fs-devel@...ts.sourceforge.net> Subject: Re: [f2fs-dev] [PATCH 1/5] f2fs: relax node version check for victim data in gc Hi all, On 2017/3/26 5:27, Jaegeuk Kim wrote: > On 03/25, Chao Yu wrote: >> Hi Jaegeuk, >> >> On 2017/3/25 15:59, Jaegeuk Kim wrote: >>> - has_not_enough_free_secs >>> node_secs: 0 dent_secs: 0 freed:0 free_segments:103 reserved:104 >>> >>> - f2fs_gc >>> - get_victim_by_default >>> alloc_mode 0, gc_mode 1, max_search 2672, offset 4654, ofs_unit 1 >>> >>> - do_garbage_collect >>> start_segno 3976, end_segno 3977 type 0 >>> >>> - is_alive >>> nid 22797, blkaddr 2131882, ofs_in_node 0, version 0x8/0x0 >>> >>> - gc_data_segment 766, segno 3976, block 512/426 not alive >>> >>> So, this patch fixes subtle corrupted case where node version does not match >>> to summary version which results in infinite loop by gc. >>> >>> Reported-by: Yunlei He <heyunlei@...wei.com> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org> >>> --- >>> fs/f2fs/gc.c | 6 ++++-- >>> 1 file changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>> index 939be88a8833..bbeee41aaf73 100644 >>> --- a/fs/f2fs/gc.c >>> +++ b/fs/f2fs/gc.c >>> @@ -551,8 +551,10 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, >>> get_node_info(sbi, nid, dni); >>> >>> if (sum->version != dni->version) { >> >> If the node was been truncated, we will increase its version number, since it >> was been truncated, so it will never be writebacked to storage, so the version >> in summary will not be updated. > The same problem I came across with a node segment: 481 get_node_info(sbi, nid, &ni); 482 if (ni.blk_addr != start_addr + off) { 483 f2fs_put_page(node_page, 1); 484 continue; 485 } Here, get victim method always selected segno 5169 for garbage collection, but this section gc failed for upper condition: gc_node_segment 494, blk_addr 1697572,start_addr 2668544,off 200 I think is same problem with is_alive function. Thanks. > That's covered by node page lock, so we shouldn't be reached out to this point. > Let's think more about this. > > Thanks, > >> So this case can happen, shouldn't we just set SBI_NEED_FSCK for the case: >> sum->version != dni->version - 1 >> >> Thanks, >> >>> - f2fs_put_page(node_page, 1); >>> - return false; >>> + f2fs_msg(sbi->sb, KERN_WARNING, >>> + "%s: valid data with mismatched node version.", >>> + __func__); >>> + set_sbi_flag(sbi, SBI_NEED_FSCK); >>> } >>> >>> *nofs = ofs_of_node(node_page); >>> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@...ts.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > . >
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