The patch titled
Subject: ocfs2: refcount: take rw_lock in ocfs2_reflink
has been added to the -mm tree. Its filename is
refcount-take-rw_lock-in-ocfs2_reflink.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/refcount-take-rw_lock-in-ocfs2_reflink.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/refcount-take-rw_lock-in-ocfs2_reflink.patch
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------------------------------------------------------
From: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
Subject: ocfs2: refcount: take rw_lock in ocfs2_reflink
This patch tries to fix this crash:
#5 [ffff88003c1cd690] do_invalid_op at ffffffff810166d5
#6 [ffff88003c1cd730] invalid_op at ffffffff8159b2de
[exception RIP: ocfs2_direct_IO_get_blocks+359]
RIP: ffffffffa05dfa27 RSP: ffff88003c1cd7e8 RFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff88003c1cdaa8 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffff880027a95000 RDI: ffff88003c79b540
RBP: ffff88003c1cd858 R8: 0000000000000000 R9: ffffffff815f6ba0
R10: 00000000000001c9 R11: 00000000000001c9 R12: ffff88002d271500
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000001000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#7 [ffff88003c1cd860] do_direct_IO at ffffffff811cd31b
#8 [ffff88003c1cd950] direct_IO_iovec at ffffffff811cde9c
#9 [ffff88003c1cd9b0] do_blockdev_direct_IO at ffffffff811ce764
#10 [ffff88003c1cdb80] __blockdev_direct_IO at ffffffff811ce7cc
#11 [ffff88003c1cdbb0] ocfs2_direct_IO at ffffffffa05df756 [ocfs2]
#12 [ffff88003c1cdbe0] generic_file_direct_write_iter at ffffffff8112f935
#13 [ffff88003c1cdc40] ocfs2_file_write_iter at ffffffffa0600ccc [ocfs2]
#14 [ffff88003c1cdd50] do_aio_write at ffffffff8119126c
#15 [ffff88003c1cddc0] aio_rw_vect_retry at ffffffff811d9bb4
#16 [ffff88003c1cddf0] aio_run_iocb at ffffffff811db880
#17 [ffff88003c1cde30] io_submit_one at ffffffff811dc238
#18 [ffff88003c1cde80] do_io_submit at ffffffff811dc437
#19 [ffff88003c1cdf70] sys_io_submit at ffffffff811dc530
#20 [ffff88003c1cdf80] system_call_fastpath at ffffffff8159a159
It crashes at
BUG_ON(create && (ext_flags & OCFS2_EXT_REFCOUNTED));
in ocfs2_direct_IO_get_blocks.
ocfs2_direct_IO_get_blocks is expecting the OCFS2_EXT_REFCOUNTED be removed in
ocfs2_prepare_inode_for_write() if it was there. But no cluster lock is taken
during the time before (or inside) ocfs2_prepare_inode_for_write() and after
ocfs2_direct_IO_get_blocks().
It can happen in this case:
Node A(which crashes) Node B
------------------------ ---------------------------
ocfs2_file_aio_write
ocfs2_prepare_inode_for_write
ocfs2_inode_lock
...
ocfs2_inode_unlock
#no refcount found
.... ocfs2_reflink
ocfs2_inode_lock
...
ocfs2_inode_unlock
#now, refcount flag set on extent
...
flush change to disk
ocfs2_direct_IO_get_blocks
ocfs2_get_clusters
#extent map miss
#buffer_head miss
read extents from disk
found refcount flag on extent
crash..
Fix:
Take rw_lock in ocfs2_reflink path
Signed-off-by: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
Reviewed-by: Mark Fasheh <mfasheh@xxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/refcounttree.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN fs/ocfs2/refcounttree.c~refcount-take-rw_lock-in-ocfs2_reflink fs/ocfs2/refcounttree.c
--- a/fs/ocfs2/refcounttree.c~refcount-take-rw_lock-in-ocfs2_reflink
+++ a/fs/ocfs2/refcounttree.c
@@ -4288,9 +4288,16 @@ static int ocfs2_reflink(struct dentry *
goto out;
}
+ error = ocfs2_rw_lock(inode, 1);
+ if (error) {
+ mlog_errno(error);
+ goto out;
+ }
+
error = ocfs2_inode_lock(inode, &old_bh, 1);
if (error) {
mlog_errno(error);
+ ocfs2_rw_unlock(inode, 1);
goto out;
}
@@ -4302,6 +4309,7 @@ static int ocfs2_reflink(struct dentry *
up_write(&OCFS2_I(inode)->ip_xattr_sem);
ocfs2_inode_unlock(inode, 1);
+ ocfs2_rw_unlock(inode, 1);
brelse(old_bh);
if (error) {
_
Patches currently in -mm which might be from wen.gang.wang@xxxxxxxxxx are
refcount-take-rw_lock-in-ocfs2_reflink.patch
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