From: alex chen <alex.chen@xxxxxxxxxx>
Subject: ocfs2: ip_alloc_sem should be taken in ocfs2_get_block()
ip_alloc_sem should be taken in ocfs2_get_block() when reading file in
DIRECT mode to prevent concurrent access to extent tree with
ocfs2_dio_end_io_write(), which may cause BUGON in the following
situation:
read file 'A' end_io of writing file 'A'
vfs_read
__vfs_read
ocfs2_file_read_iter
generic_file_read_iter
ocfs2_direct_IO
__blockdev_direct_IO
do_blockdev_direct_IO
do_direct_IO
get_more_blocks
ocfs2_get_block
ocfs2_extent_map_get_blocks
ocfs2_get_clusters
ocfs2_get_clusters_nocache()
ocfs2_search_extent_list
return the index of record which
contains the v_cluster, that is
v_cluster > rec[i]->e_cpos.
ocfs2_dio_end_io
ocfs2_dio_end_io_write
down_write(&oi->ip_alloc_sem);
ocfs2_mark_extent_written
ocfs2_change_extent_flag
ocfs2_split_extent
...
--> modify the rec[i]->e_cpos, resulting
in v_cluster < rec[i]->e_cpos.
BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos))
[alex.chen@xxxxxxxxxx: v3]
Link: http://lkml.kernel.org/r/59EF3614.6050008@xxxxxxxxxx
Link: http://lkml.kernel.org/r/59EF3614.6050008@xxxxxxxxxx
Fixes: c15471f79506 ("ocfs2: fix sparse file & data ordering issue in direct io")
Signed-off-by: Alex Chen <alex.chen@xxxxxxxxxx>
Reviewed-by: Jun Piao <piaojun@xxxxxxxxxx>
Reviewed-by: Joseph Qi <jiangqi903@xxxxxxxxx>
Reviewed-by: Gang He <ghe@xxxxxxxx>
Acked-by: Changwei Ge <ge.changwei@xxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/aops.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff -puN fs/ocfs2/aops.c~ocfs2-the-ip_alloc_sem-should-be-taken-in-ocfs2_get_block fs/ocfs2/aops.c
--- a/fs/ocfs2/aops.c~ocfs2-the-ip_alloc_sem-should-be-taken-in-ocfs2_get_block
+++ a/fs/ocfs2/aops.c
@@ -134,6 +134,19 @@ bail:
return err;
}
+static int ocfs2_lock_get_block(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ int ret = 0;
+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
+
+ down_read(&oi->ip_alloc_sem);
+ ret = ocfs2_get_block(inode, iblock, bh_result, create);
+ up_read(&oi->ip_alloc_sem);
+
+ return ret;
+}
+
int ocfs2_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
@@ -2128,7 +2141,7 @@ static void ocfs2_dio_free_write_ctx(str
* called like this: dio->get_blocks(dio->inode, fs_startblk,
* fs_count, map_bh, dio->rw == WRITE);
*/
-static int ocfs2_dio_get_block(struct inode *inode, sector_t iblock,
+static int ocfs2_dio_wr_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
@@ -2154,12 +2167,9 @@ static int ocfs2_dio_get_block(struct in
* while file size will be changed.
*/
if (pos + total_len <= i_size_read(inode)) {
- down_read(&oi->ip_alloc_sem);
- /* This is the fast path for re-write. */
- ret = ocfs2_get_block(inode, iblock, bh_result, create);
-
- up_read(&oi->ip_alloc_sem);
+ /* This is the fast path for re-write. */
+ ret = ocfs2_lock_get_block(inode, iblock, bh_result, create);
if (buffer_mapped(bh_result) &&
!buffer_new(bh_result) &&
ret == 0)
@@ -2424,9 +2434,9 @@ static ssize_t ocfs2_direct_IO(struct ki
return 0;
if (iov_iter_rw(iter) == READ)
- get_block = ocfs2_get_block;
+ get_block = ocfs2_lock_get_block;
else
- get_block = ocfs2_dio_get_block;
+ get_block = ocfs2_dio_wr_get_block;
return __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
iter, get_block,
_
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
