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authorJiufei Xue <jiufei.xue@linux.alibaba.com>2019-04-06 18:57:40 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-22 07:37:41 +0200
commit001fe0dab4eacd9e714b7c9de5f13af2bb3c3e1a (patch)
treecf26afdc77829797021bdefbcc61089c960210f4 /fs/jbd2
parent0fd2df64f14297eb469987059929e3ae793f124a (diff)
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jbd2: check superblock mapped prior to committing
commit 742b06b5628f2cd23cb51a034cb54dc33c6162c5 upstream. We hit a BUG at fs/buffer.c:3057 if we detached the nbd device before unmounting ext4 filesystem. The typical chain of events leading to the BUG: jbd2_write_superblock submit_bh submit_bh_wbc BUG_ON(!buffer_mapped(bh)); The block device is removed and all the pages are invalidated. JBD2 was trying to write journal superblock to the block device which is no longer present. Fix this by checking the journal superblock's buffer head prior to submitting. Reported-by: Eric Ren <renzhen@linux.alibaba.com> Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/jbd2')
-rw-r--r--fs/jbd2/journal.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 88f2a49338a1..9e618777c699 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1366,6 +1366,10 @@ static int jbd2_write_superblock(journal_t *journal, int write_flags)
journal_superblock_t *sb = journal->j_superblock;
int ret;
+ /* Buffer got discarded which means block device got invalidated */
+ if (!buffer_mapped(bh))
+ return -EIO;
+
trace_jbd2_write_superblock(journal, write_flags);
if (!(journal->j_flags & JBD2_BARRIER))
write_flags &= ~(REQ_FUA | REQ_PREFLUSH);