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ocfs2: ip_alloc_sem should be taken in ocfs2_get_block()

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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@huawei.com: v3]
  Link: http://lkml.kernel.org/r/59EF3614.6050008@huawei.com
Link: http://lkml.kernel.org/r/59EF3614.6050008@huawei.com
Fixes: c15471f795 ("ocfs2: fix sparse file & data ordering issue in direct io")
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Reviewed-by: Gang He <ghe@suse.com>
Acked-by: Changwei Ge <ge.changwei@h3c.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
alex chen 2017-11-15 17:31:44 -08:00 committed by Linus Torvalds
parent 28f5a8a7c0
commit 3e4c56d41e
1 changed files with 18 additions and 8 deletions
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26
fs/ocfs2/aops.c
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@ -134,6 +134,19 @@ static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
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(struct inode *inode,
* 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 inode *inode, sector_t iblock,
* 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);
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 kiocb *iocb, struct iov_iter *iter)
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,