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authorSteven Whitehouse <swhiteho@redhat.com>2009-12-08 05:25:33 -0500
committerSteven Whitehouse <swhiteho@redhat.com>2010-01-08 08:42:27 -0500
commit56aa616a03feca630d5afce647367a5d8cfc67b8 (patch)
treea4b4feb0d2ac0f329b98748445adb90a6458a2e9 /fs/gfs2/file.c
parent74d2e4f8d79ae0c4b6ec027958d5b18058662eea (diff)
GFS2: Ensure uptodate inode size when using O_APPEND
The VFS reads the inode size during generic_file_aio_write() but with no locking around it. In order to get the expected result from O_APPEND opens, this patch updated the inode size before calling generic_file_aio_write() There is of course still a race here, in that there is nothing to prevent another node coming in and extending the file in the mean time. On the other hand, when used with file locking this will ensure that the expected results are obtained. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2/file.c')
-rw-r--r--fs/gfs2/file.c38
1 files changed, 36 insertions, 2 deletions
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 4eb308aa3234..a6abbae8a278 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -569,6 +569,40 @@ static int gfs2_fsync(struct file *file, struct dentry *dentry, int datasync)
569 return ret; 569 return ret;
570} 570}
571 571
572/**
573 * gfs2_file_aio_write - Perform a write to a file
574 * @iocb: The io context
575 * @iov: The data to write
576 * @nr_segs: Number of @iov segments
577 * @pos: The file position
578 *
579 * We have to do a lock/unlock here to refresh the inode size for
580 * O_APPEND writes, otherwise we can land up writing at the wrong
581 * offset. There is still a race, but provided the app is using its
582 * own file locking, this will make O_APPEND work as expected.
583 *
584 */
585
586static ssize_t gfs2_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
587 unsigned long nr_segs, loff_t pos)
588{
589 struct file *file = iocb->ki_filp;
590
591 if (file->f_flags & O_APPEND) {
592 struct dentry *dentry = file->f_dentry;
593 struct gfs2_inode *ip = GFS2_I(dentry->d_inode);
594 struct gfs2_holder gh;
595 int ret;
596
597 ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
598 if (ret)
599 return ret;
600 gfs2_glock_dq_uninit(&gh);
601 }
602
603 return generic_file_aio_write(iocb, iov, nr_segs, pos);
604}
605
572#ifdef CONFIG_GFS2_FS_LOCKING_DLM 606#ifdef CONFIG_GFS2_FS_LOCKING_DLM
573 607
574/** 608/**
@@ -711,7 +745,7 @@ const struct file_operations gfs2_file_fops = {
711 .read = do_sync_read, 745 .read = do_sync_read,
712 .aio_read = generic_file_aio_read, 746 .aio_read = generic_file_aio_read,
713 .write = do_sync_write, 747 .write = do_sync_write,
714 .aio_write = generic_file_aio_write, 748 .aio_write = gfs2_file_aio_write,
715 .unlocked_ioctl = gfs2_ioctl, 749 .unlocked_ioctl = gfs2_ioctl,
716 .mmap = gfs2_mmap, 750 .mmap = gfs2_mmap,
717 .open = gfs2_open, 751 .open = gfs2_open,
@@ -741,7 +775,7 @@ const struct file_operations gfs2_file_fops_nolock = {
741 .read = do_sync_read, 775 .read = do_sync_read,
742 .aio_read = generic_file_aio_read, 776 .aio_read = generic_file_aio_read,
743 .write = do_sync_write, 777 .write = do_sync_write,
744 .aio_write = generic_file_aio_write, 778 .aio_write = gfs2_file_aio_write,
745 .unlocked_ioctl = gfs2_ioctl, 779 .unlocked_ioctl = gfs2_ioctl,
746 .mmap = gfs2_mmap, 780 .mmap = gfs2_mmap,
747 .open = gfs2_open, 781 .open = gfs2_open,