On Thu, Jun 20, 2013 at 04:23:59PM +0800, shencanquan wrote:
> llseek requires ocfs2 inode lock for updating the file size in SEEK_END.
> because the file size maybe update on another node.
> if it not . after call llseek in SEEK_END. the position is old.
>
> this bug can be reproduce the following scenario:
> at first ,we dd a test fileA,the file size is 10k.
> on NodeA:
> ---------
> 1) open the test fileA, lseek the end of file. and print the position.
> 2) close the test fileA
>
> on NodeB:
> 1) open the test fileA, append the 5k data to test FileA.
> 2) lseek the end of file. and print the position.
> 3) close file.
>
> at first we run the test program1 on NodeA , the result is 10k.
> and then run the test program2 on NodeB, the result is 15k.
> at last, we run the test program1 on NodeA again, the result is 10k.
>
> after apply this patch. the three step result is 15k.
>
> Signed-off-by: jensen <shencanq...@huawei.com>
> ---
> fs/ocfs2/file.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index ff54014..3afd24c 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2626,7 +2626,16 @@ static loff_t ocfs2_file_llseek(struct file *file,
> loff_t offset, int whence)
> case SEEK_SET:
> break;
> case SEEK_END:
> + /* SEEK_END requires the OCFS2 inode lock for the file
> + * because it references the file's size.
> + */
> + ret = ocfs2_inode_lock(inode, NULL, 0);
> + if (ret < 0) {
> + mlog_errno(ret);
> + goto out;
> + }
> offset += inode->i_size;
> + ocfs2_inode_unlock(inode, 0);
Why wouldn't ocfs2_rw_lock() work? Just because we dont get the LVB
from it?
Joel
> break;
> case SEEK_CUR:
> if (offset == 0) {
> --
> 1.7.9.7
>
>
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> Ocfs2-devel@oss.oracle.com
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