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[XFS] Start writeout earlier (on last close) in the case where we have a

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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>
This commit is contained in:
Nathan Scott
2006-06-09 15:27:16 +10:00
parent 59c1b082f5
commit 7d4fb40ad7
5 changed files with 114 additions and 94 deletions
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88
fs/xfs/xfs_vnodeops.c
View File

@@ -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 @@ xfs_open(
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 @@ xfs_setattr(
((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.
@@ -936,6 +954,13 @@ xfs_access(
}
/*
* 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 @@ xfs_inactive_symlink_local(
return 0;
}
/*
*
*/
STATIC int
xfs_inactive_attrs(
xfs_inode_t *ip,
@@ -1531,10 +1553,10 @@ xfs_release(
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 @@ xfs_release(
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 @@ xfs_inode_flush(
return error;
}
int
xfs_set_dmattrs (
bhv_desc_t *bdp,
@@ -3786,10 +3805,6 @@ xfs_set_dmattrs (
return error;
}
/*
* xfs_reclaim
*/
STATIC int
xfs_reclaim(
bhv_desc_t *bdp)
@@ -4645,6 +4660,7 @@ xfs_change_file_space(
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,