On 17/10/20 17:03, alex chen wrote:
> The 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
> ocfs2_get_clusters_nocache()->BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos))
>
> Signed-off-by: Alex Chen <alex.c...@huawei.com>
> Reviewed-by: Jun Piao <piao...@huawei.com>
>
> ---
> fs/ocfs2/aops.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index 88a31e9..5cb939f 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -134,6 +134,19 @@ static int ocfs2_symlink_get_block(struct inode *inode,
> sector_t iblock,
> return err;
> }
>
> +static int ocfs2_get_block_lock(struct inode *inode, sector_t iblock,
> + struct buffer_head *bh_result, int create)
> +{
> + int ret;
> + 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)
> {
> @@ -2154,12 +2167,8 @@ 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_get_block_lock(inode, iblock, bh_result, create);
> if (buffer_mapped(bh_result) &&
> !buffer_new(bh_result) &&
> ret == 0)
> @@ -2424,7 +2433,7 @@ 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_get_block_lock;
ocfs2_lock_get_block may be better.
Thanks,
Joseph
> else
> get_block = ocfs2_dio_get_block;
>
> -- 1.9.5.msysgit.1
>
>
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