From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Becker Date: Sat, 29 Jun 2013 14:37:45 +0100 Subject: [Ocfs2-devel] [PATCH] ocfs2: llseek requires to ocfs2 inode lock for the file in SEEK_END In-Reply-To: <51C2BC1F.2010106@huawei.com> References: <51C2BC1F.2010106@huawei.com> Message-ID: <20130629133745.GL13405@ZenIV.linux.org.uk> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com 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 > --- > 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 > > > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel at oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel --