As I mentioned in the bug-report, when the file size is
not n * BUFFERSIZE, this file cannot be read correctly
and the system will crash or hang up.
After investigation, I fount that data_len should be
checked before lock_extent, in order to prevent the
situation that when it comes to the file end,
diocb->lockstart changes to lockend+1, then lock_extent
will cause system's crash or hang.
So move the data_len's check ahead.
Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
---
fs/btrfs/dio.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/dio.c b/fs/btrfs/dio.c
index c930ff5..7178a25 100644
--- a/fs/btrfs/dio.c
+++ b/fs/btrfs/dio.c
@@ -517,11 +517,6 @@ static void btrfs_dio_read(struct btrfs_diocb *diocb)
lockend = ALIGN(end, blocksize) - 1;
getlock:
- /* writeout everything we read for checksum or compressed extents */
- filemap_write_and_wait_range(diocb->inode->i_mapping,
- diocb->lockstart, lockend);
- lock_extent(io_tree, diocb->lockstart, lockend, GFP_NOFS);
-
data_len = min_t(u64, end, i_size_read(diocb->inode));
if (data_len <= diocb->start) {
/* whatever we finished (or 0) is returned past EOF */
@@ -529,6 +524,11 @@ getlock:
}
data_len -= diocb->start;
+ /* writeout everything we read for checksum or compressed extents */
+ filemap_write_and_wait_range(diocb->inode->i_mapping,
+ diocb->lockstart, lockend);
+ lock_extent(io_tree, diocb->lockstart, lockend, GFP_NOFS);
+
safe_to_read = 0;
while (data_len && !diocb->error) { /* error in reaper stops submit */
struct extent_map *em;
--
1.6.2.5
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
