An user reported this, it is because that lseek's SEEK_SET/SEEK_CUR/SEEK_END
allow a negative value for @offset, but btrfs's SEEK_DATA/SEEK_HOLE don't
prepare for that and convert the negative @offset into unsigned type,
so we get (end < start) warning.
[ 1269.835374] ------------[ cut here ]------------
[ 1269.836809] WARNING: CPU: 0 PID: 1241 at fs/btrfs/extent_io.c:430
insert_state+0x11d/0x140()
[ 1269.838816] BTRFS: end < start 4094 18446744073709551615
[ 1269.840334] CPU: 0 PID: 1241 Comm: a.out Tainted: G W 3.16.0+
#306
[ 1269.858229] Call Trace:
[ 1269.858612] [<ffffffff81801a69>] dump_stack+0x4e/0x68
[ 1269.858952] [<ffffffff8107894c>] warn_slowpath_common+0x8c/0xc0
[ 1269.859416] [<ffffffff81078a36>] warn_slowpath_fmt+0x46/0x50
[ 1269.859929] [<ffffffff813b0fbd>] insert_state+0x11d/0x140
[ 1269.860409] [<ffffffff813b1396>] __set_extent_bit+0x3b6/0x4e0
[ 1269.860805] [<ffffffff813b21c7>] lock_extent_bits+0x87/0x200
[ 1269.861697] [<ffffffff813a5b28>] btrfs_file_llseek+0x148/0x2a0
[ 1269.862168] [<ffffffff811f201e>] SyS_lseek+0xae/0xc0
[ 1269.862620] [<ffffffff8180b212>] system_call_fastpath+0x16/0x1b
[ 1269.862970] ---[ end trace 4d33ea885832054b ]---
This adds a check for that, if we find the unsigned type @offset is greater
than inode's size, we get to skip trying to find extent maps.
Reported-by: Toralf Förster <toralf.foers...@gmx.de>
Signed-off-by: Liu Bo <bo.li....@oracle.com>
---
fs/btrfs/file.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1f2b99c..a370916 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2644,6 +2644,13 @@ static int find_desired_extent(struct inode *inode,
loff_t *offset, int whence)
u64 len = i_size_read(inode);
int ret = 0;
+ /*
+ * *offset can be negative, so start is greater than inode->i_size in
+ * this case, and we can skip finding em.
+ */
+ if (start >= inode->i_size)
+ goto out;
+
lockend = max_t(u64, root->sectorsize, lockend);
if (lockend <= lockstart)
lockend = lockstart + root->sectorsize;
@@ -2681,14 +2688,15 @@ static int find_desired_extent(struct inode *inode,
loff_t *offset, int whence)
cond_resched();
}
free_extent_map(em);
+ unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+ &cached_state, GFP_NOFS);
+out:
if (!ret) {
if (whence == SEEK_DATA && start >= inode->i_size)
ret = -ENXIO;
else
*offset = min_t(loff_t, start, inode->i_size);
}
- unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
- &cached_state, GFP_NOFS);
return ret;
}
--
1.8.1.4
--
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