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 assumes that btrfs starts finding DATA/HOLE from the beginning of file if the assigned @offset is negative. Also we add alignment for lock_extent_bits 's range. Reported-by: Toralf Förster <toralf.foerster@gmx.de> Signed-off-by: Liu Bo <bo.li.liu@oracle.com> --- fs/btrfs/file.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index ff1cc03..68dd92c 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2621,23 +2621,28 @@ static int find_desired_extent(struct inode *inode, loff_t *offset, int whence) struct btrfs_root *root = BTRFS_I(inode)->root; struct extent_map *em = NULL; struct extent_state *cached_state = NULL; - u64 lockstart = *offset; - u64 lockend = i_size_read(inode); - u64 start = *offset; - u64 len = i_size_read(inode); + u64 lockstart; + u64 lockend; + u64 start; + u64 len; int ret = 0; - lockend = max_t(u64, root->sectorsize, lockend); + if (inode->i_size == 0) + return -ENXIO; + + /* + * *offset can be negative, in this case we start finding DATA/HOLE from + * the very start of the file. + */ + start = max_t(loff_t, 0, *offset); + + lockstart = round_down(start, root->sectorsize); + lockend = round_up(i_size_read(inode), root->sectorsize); if (lockend <= lockstart) lockend = lockstart + root->sectorsize; - lockend--; len = lockend - lockstart + 1; - len = max_t(u64, len, root->sectorsize); - if (inode->i_size == 0) - return -ENXIO; - lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0, &cached_state); -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html