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Wed, 13 Nov 2019 10:31:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1573641074; bh=/66u/Suwke1zMwFS5nxwNNZ4s1ARpfkENpmO/QNhmqc=; h=From:To:Cc:Subject:Date:From; b=Nr5MnjmbZ5sAfMwxAqXAepG0Es1g8ocLUj/anOxjmBb5lZxdQDdhAFyjmJDcFwJ9E HNpWSGu/noC7Tut/mKqQLFn4bETwV0P3sh2JeVO7/QSvsRO4/y8lHu1cILolmJadIq vOB70Rs3CFL0UxxSxdvmWPfvaFHvCTbDYVvQ7kv8= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0D3A160592 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=stummala@codeaurora.org From: Sahitya Tummala To: Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net Date: Wed, 13 Nov 2019 16:01:03 +0530 Message-Id: <1573641063-21232-1-git-send-email-stummala@codeaurora.org> X-Mailer: git-send-email 1.9.1 X-Headers-End: 1iUpvo-0018pr-Na Subject: [f2fs-dev] [PATCH] f2fs: Fix deadlock in f2fs_gc() context during atomic files handling X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net The FS got stuck in the below stack when the storage is almost full/dirty condition (when FG_GC is being done). schedule_timeout io_schedule_timeout congestion_wait f2fs_drop_inmem_pages_all f2fs_gc f2fs_balance_fs __write_node_page f2fs_fsync_node_pages f2fs_do_sync_file f2fs_ioctl The root cause for this issue is there is a potential infinite loop in f2fs_drop_inmem_pages_all() for the case where gc_failure is true and when there an inode whose i_gc_failures[GC_FAILURE_ATOMIC] is not set. Fix this by keeping track of the total atomic files currently opened and using that to exit from this condition. Fix-suggested-by: Chao Yu Signed-off-by: Chao Yu Signed-off-by: Sahitya Tummala --- v2: - change fix as per Chao's suggestion - decrement sbi->atomic_files protected under sbi->inode_lock[ATOMIC_FILE] and only when atomic flag is cleared for the first time, otherwise, the count goes to an invalid/high value as f2fs_drop_inmem_pages() can be called from two contexts at the same time. fs/f2fs/f2fs.h | 1 + fs/f2fs/file.c | 1 + fs/f2fs/segment.c | 21 +++++++++++++++------ 3 files changed, 17 insertions(+), 6 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index c681f51..e04a665 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1297,6 +1297,7 @@ struct f2fs_sb_info { unsigned int gc_mode; /* current GC state */ unsigned int next_victim_seg[2]; /* next segment in victim section */ /* for skip statistic */ + unsigned int atomic_files; /* # of opened atomic file */ unsigned long long skipped_atomic_files[2]; /* FG_GC and BG_GC */ unsigned long long skipped_gc_rwsem; /* FG_GC only */ diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index f6c038e..22c4949 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1919,6 +1919,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) spin_lock(&sbi->inode_lock[ATOMIC_FILE]); if (list_empty(&fi->inmem_ilist)) list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]); + sbi->atomic_files++; spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); /* add inode in inmem_list first and set atomic_file */ diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index da830fc..0b7a33b 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -288,6 +288,8 @@ void f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure) struct list_head *head = &sbi->inode_list[ATOMIC_FILE]; struct inode *inode; struct f2fs_inode_info *fi; + unsigned int count = sbi->atomic_files; + unsigned int looped = 0; next: spin_lock(&sbi->inode_lock[ATOMIC_FILE]); if (list_empty(head)) { @@ -296,22 +298,26 @@ void f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure) } fi = list_first_entry(head, struct f2fs_inode_info, inmem_ilist); inode = igrab(&fi->vfs_inode); + if (inode) + list_move_tail(&fi->inmem_ilist, head); spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); if (inode) { if (gc_failure) { - if (fi->i_gc_failures[GC_FAILURE_ATOMIC]) - goto drop; - goto skip; + if (!fi->i_gc_failures[GC_FAILURE_ATOMIC]) + goto skip; } -drop: set_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); f2fs_drop_inmem_pages(inode); +skip: iput(inode); } -skip: congestion_wait(BLK_RW_ASYNC, HZ/50); cond_resched(); + if (gc_failure) { + if (++looped >= count) + return; + } goto next; } @@ -327,13 +333,16 @@ void f2fs_drop_inmem_pages(struct inode *inode) mutex_unlock(&fi->inmem_lock); } - clear_inode_flag(inode, FI_ATOMIC_FILE); fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; stat_dec_atomic_write(inode); spin_lock(&sbi->inode_lock[ATOMIC_FILE]); if (!list_empty(&fi->inmem_ilist)) list_del_init(&fi->inmem_ilist); + if (f2fs_is_atomic_file(inode)) { + clear_inode_flag(inode, FI_ATOMIC_FILE); + sbi->atomic_files--; + } spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); } -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project. _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel