Messages in this thread | | | Subject | Re: [PATCH] ocfs2: fix the oops problem when write cloned file | From | Changwei Ge <> | Date | Mon, 3 Feb 2020 13:19:23 +0800 |
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Sure. I will try to allocate some time for this change.
- Changwei
On 2/3/20 10:17 AM, Gang He wrote: > Hello Joseph, Changwei, Sunny and all, > > Could you help to review this patch? > This patch will fix the oops problem caused by write ocfs2 clone files. > The root cause is inode buffer head is NULL when calling ocfs2_refcount_cow. > Secondly, we should use EX meta lock when calling ocfs2_refcount_cow. > > Thanks a lot. > Gang > > ________________________________________ > From: Gang He <GHe@suse.com> > Sent: Tuesday, January 21, 2020 1:02 PM > To: mark@fasheh.com; jlbec@evilplan.org; joseph.qi@linux.alibaba.com > Cc: Gang He; linux-kernel@vger.kernel.org; ocfs2-devel@oss.oracle.com; akpm@linux-foundation.org > Subject: [PATCH] ocfs2: fix the oops problem when write cloned file > > Writing a cloned file triggers a kernel oops and the user-space > command process is also killed by the system. > The bug can be reproduced stably, e.g. > 1)create a file under ocfs2 file system directory. > journalctl -b > aa.txt > 2)create a cloned file for this file. > reflink aa.txt bb.txt > 3)write the cloned file with dd command. > dd if=/dev/zero of=bb.txt bs=512 count=1 conv=notrunc > > The dd command is killed by the kernel, then you can see the oops > message via dmesg command. > > [ 463.875404] BUG: kernel NULL pointer dereference, address: 0000000000000028 > [ 463.875413] #PF: supervisor read access in kernel mode > [ 463.875416] #PF: error_code(0x0000) - not-present page > [ 463.875418] PGD 0 P4D 0 > [ 463.875425] Oops: 0000 [#1] SMP PTI > [ 463.875431] CPU: 1 PID: 2291 Comm: dd Tainted: G OE 5.3.16-2-default > [ 463.875433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > [ 463.875500] RIP: 0010:ocfs2_refcount_cow+0xa4/0x5d0 [ocfs2] > [ 463.875505] Code: 06 89 6c 24 38 89 eb f6 44 24 3c 02 74 be 49 8b 47 28 > [ 463.875508] RSP: 0018:ffffa2cb409dfce8 EFLAGS: 00010202 > [ 463.875512] RAX: ffff8b1ebdca8000 RBX: 0000000000000001 RCX: ffff8b1eb73a9df0 > [ 463.875515] RDX: 0000000000056a01 RSI: 0000000000000000 RDI: 0000000000000000 > [ 463.875517] RBP: 0000000000000001 R08: ffff8b1eb73a9de0 R09: 0000000000000000 > [ 463.875520] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 > [ 463.875522] R13: ffff8b1eb922f048 R14: 0000000000000000 R15: ffff8b1eb922f048 > [ 463.875526] FS: 00007f8f44d15540(0000) GS:ffff8b1ebeb00000(0000) knlGS:0000000000000000 > [ 463.875529] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 463.875532] CR2: 0000000000000028 CR3: 000000003c17a000 CR4: 00000000000006e0 > [ 463.875546] Call Trace: > [ 463.875596] ? ocfs2_inode_lock_full_nested+0x18b/0x960 [ocfs2] > [ 463.875648] ocfs2_file_write_iter+0xaf8/0xc70 [ocfs2] > [ 463.875672] new_sync_write+0x12d/0x1d0 > [ 463.875688] vfs_write+0xad/0x1a0 > [ 463.875697] ksys_write+0xa1/0xe0 > [ 463.875710] do_syscall_64+0x60/0x1f0 > [ 463.875743] entry_SYSCALL_64_after_hwframe+0x49/0xbe > [ 463.875758] RIP: 0033:0x7f8f4482ed44 > [ 463.875762] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00 > [ 463.875765] RSP: 002b:00007fff300a79d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > [ 463.875769] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8f4482ed44 > [ 463.875771] RDX: 0000000000000200 RSI: 000055f771b5c000 RDI: 0000000000000001 > [ 463.875774] RBP: 0000000000000200 R08: 00007f8f44af9c78 R09: 0000000000000003 > [ 463.875776] R10: 000000000000089f R11: 0000000000000246 R12: 000055f771b5c000 > [ 463.875779] R13: 0000000000000200 R14: 0000000000000000 R15: 000055f771b5c000 > > This regression problem was introduced by commit e74540b28556 ("ocfs2: > protect extent tree in ocfs2_prepare_inode_for_write()"). > > Fixes: e74540b28556 ("ocfs2: protect extent tree in ocfs2_prepare_inode_for_write()"). > Signed-off-by: Gang He <ghe@suse.com> > --- > fs/ocfs2/file.c | 14 ++++++-------- > 1 file changed, 6 insertions(+), 8 deletions(-) > > diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c > index 9876db52913a..6cd5e4924e4d 100644 > --- a/fs/ocfs2/file.c > +++ b/fs/ocfs2/file.c > @@ -2101,17 +2101,15 @@ static int ocfs2_is_io_unaligned(struct inode *inode, size_t count, loff_t pos) > static int ocfs2_inode_lock_for_extent_tree(struct inode *inode, > struct buffer_head **di_bh, > int meta_level, > - int overwrite_io, > int write_sem, > int wait) > { > int ret = 0; > > if (wait) > - ret = ocfs2_inode_lock(inode, NULL, meta_level); > + ret = ocfs2_inode_lock(inode, di_bh, meta_level); > else > - ret = ocfs2_try_inode_lock(inode, > - overwrite_io ? NULL : di_bh, meta_level); > + ret = ocfs2_try_inode_lock(inode, di_bh, meta_level); > if (ret < 0) > goto out; > > @@ -2136,6 +2134,7 @@ static int ocfs2_inode_lock_for_extent_tree(struct inode *inode, > > out_unlock: > brelse(*di_bh); > + *di_bh = NULL; > ocfs2_inode_unlock(inode, meta_level); > out: > return ret; > @@ -2177,7 +2176,6 @@ static int ocfs2_prepare_inode_for_write(struct file *file, > ret = ocfs2_inode_lock_for_extent_tree(inode, > &di_bh, > meta_level, > - overwrite_io, > write_sem, > wait); > if (ret < 0) { > @@ -2233,13 +2231,13 @@ static int ocfs2_prepare_inode_for_write(struct file *file, > &di_bh, > meta_level, > write_sem); > + meta_level = 1; > + write_sem = 1; > ret = ocfs2_inode_lock_for_extent_tree(inode, > &di_bh, > meta_level, > - overwrite_io, > - 1, > + write_sem, > wait); > - write_sem = 1; > if (ret < 0) { > if (ret != -EAGAIN) > mlog_errno(ret); > -- > 2.12.3 >
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