[XFS] Start writeout earlier (on last close) in the case where we have a
truncate down followed by delayed allocation (buffered writes) - worst
case scenario for the notorious NULL files problem. This reduces the
window where we are exposed to that problem significantly.
SGI-PV: 917976
SGI-Modid: xfs-linux-melb:xfs-kern:26100a
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index cb36a56..35906ba 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -16,8 +16,6 @@
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
-#include <linux/capability.h>
-
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
@@ -58,32 +56,14 @@
#include "xfs_log_priv.h"
#include "xfs_mac.h"
-
-/*
- * The maximum pathlen is 1024 bytes. Since the minimum file system
- * blocksize is 512 bytes, we can get a max of 2 extents back from
- * bmapi.
- */
-#define SYMLINK_MAPS 2
-
-/*
- * For xfs, we check that the file isn't too big to be opened by this kernel.
- * No other open action is required for regular files. Devices are handled
- * through the specfs file system, pipes through fifofs. Device and
- * fifo vnodes are "wrapped" by specfs and fifofs vnodes, respectively,
- * when a new vnode is first looked up or created.
- */
STATIC int
xfs_open(
bhv_desc_t *bdp,
cred_t *credp)
{
int mode;
- vnode_t *vp;
- xfs_inode_t *ip;
-
- vp = BHV_TO_VNODE(bdp);
- ip = XFS_BHVTOI(bdp);
+ vnode_t *vp = BHV_TO_VNODE(bdp);
+ xfs_inode_t *ip = XFS_BHVTOI(bdp);
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
return XFS_ERROR(EIO);
@@ -101,6 +81,36 @@
return 0;
}
+STATIC int
+xfs_close(
+ bhv_desc_t *bdp,
+ int flags,
+ lastclose_t lastclose,
+ cred_t *credp)
+{
+ vnode_t *vp = BHV_TO_VNODE(bdp);
+ xfs_inode_t *ip = XFS_BHVTOI(bdp);
+ int error = 0;
+
+ if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+ return XFS_ERROR(EIO);
+
+ if (lastclose != L_TRUE || !VN_ISREG(vp))
+ return 0;
+
+ /*
+ * If we previously truncated this file and removed old data in
+ * the process, we want to initiate "early" writeout on the last
+ * close. This is an attempt to combat the notorious NULL files
+ * problem which is particularly noticable from a truncate down,
+ * buffered (re-)write (delalloc), followed by a crash. What we
+ * are effectively doing here is significantly reducing the time
+ * window where we'd otherwise be exposed to that problem.
+ */
+ if (VUNTRUNCATE(vp) && VN_DIRTY(vp) && ip->i_delayed_blks > 0)
+ VOP_FLUSH_PAGES(vp, 0, -1, XFS_B_ASYNC, FI_NONE, error);
+ return error;
+}
/*
* xfs_getattr
@@ -665,9 +675,17 @@
((ip->i_d.di_nlink != 0 ||
!(mp->m_flags & XFS_MOUNT_WSYNC))
? 1 : 0));
- if (code) {
+ if (code)
goto abort_return;
- }
+ /*
+ * Truncated "down", so we're removing references
+ * to old data here - if we now delay flushing for
+ * a long time, we expose ourselves unduly to the
+ * notorious NULL files problem. So, we mark this
+ * vnode and flush it when the file is closed, and
+ * do not wait the usual (long) time for writeout.
+ */
+ VTRUNCATE(vp);
}
/*
* Have to do this even if the file's size doesn't change.
@@ -937,6 +955,13 @@
/*
+ * The maximum pathlen is 1024 bytes. Since the minimum file system
+ * blocksize is 512 bytes, we can get a max of 2 extents back from
+ * bmapi.
+ */
+#define SYMLINK_MAPS 2
+
+/*
* xfs_readlink
*
*/
@@ -1470,9 +1495,6 @@
return 0;
}
-/*
- *
- */
STATIC int
xfs_inactive_attrs(
xfs_inode_t *ip,
@@ -1531,10 +1553,10 @@
vp = BHV_TO_VNODE(bdp);
ip = XFS_BHVTOI(bdp);
+ mp = ip->i_mount;
- if (!VN_ISREG(vp) || (ip->i_d.di_mode == 0)) {
+ if (!VN_ISREG(vp) || (ip->i_d.di_mode == 0))
return 0;
- }
/* If this is a read-only mount, don't do this (would generate I/O) */
if (vp->v_vfsp->vfs_flag & VFS_RDONLY)
@@ -1546,8 +1568,6 @@
return 0;
#endif
- mp = ip->i_mount;
-
if (ip->i_d.di_nlink != 0) {
if ((((ip->i_d.di_mode & S_IFMT) == S_IFREG) &&
((ip->i_d.di_size > 0) || (VN_CACHED(vp) > 0 ||
@@ -3745,7 +3765,6 @@
return error;
}
-
int
xfs_set_dmattrs (
bhv_desc_t *bdp,
@@ -3786,10 +3805,6 @@
return error;
}
-
-/*
- * xfs_reclaim
- */
STATIC int
xfs_reclaim(
bhv_desc_t *bdp)
@@ -4645,6 +4660,7 @@
vnodeops_t xfs_vnodeops = {
BHV_IDENTITY_INIT(VN_BHV_XFS,VNODE_POSITION_XFS),
.vop_open = xfs_open,
+ .vop_close = xfs_close,
.vop_read = xfs_read,
#ifdef HAVE_SENDFILE
.vop_sendfile = xfs_sendfile,