[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>

5 files changed, 114 insertions, 94 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 5835e699a7fc..c0a904316854 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -1157,6 +1157,18 @@ out_unlock:
         return error;
 }
 
+STATIC int
+xfs_vm_writepages(
+        struct address_space    *mapping,
+        struct writeback_control *wbc)
+{
+        struct vnode            *vp = vn_from_inode(mapping->host);
+
+        if (VN_TRUNC(vp))
+                VUNTRUNCATE(vp);
+        return generic_writepages(mapping, wbc);
+}
+
 /*
  * Called to move a page into cleanable state - and from there
  * to be released. Possibly the page is already clean. We always
@@ -1451,6 +1463,7 @@ struct address_space_operations xfs_address_space_operations = {
         .readpage               = xfs_vm_readpage,
         .readpages              = xfs_vm_readpages,
         .writepage              = xfs_vm_writepage,
+        .writepages             = xfs_vm_writepages,
         .sync_page              = block_sync_page,
         .releasepage            = xfs_vm_releasepage,
         .invalidatepage         = xfs_vm_invalidatepage,
diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index 7c9f7598807f..97615cc74ef5 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -324,6 +324,17 @@ xfs_file_open(
 }
 
 STATIC int
+xfs_file_close(
+        struct file     *filp)
+{
+        vnode_t         *vp = vn_from_inode(filp->f_dentry->d_inode);
+        int             error;
+
+        VOP_CLOSE(vp, 0, file_count(filp) > 1 ? L_FALSE : L_TRUE, NULL, error);
+        return -error;
+}
+
+STATIC int
 xfs_file_release(
         struct inode    *inode,
         struct file     *filp)
@@ -349,6 +360,8 @@ xfs_file_fsync(
 
         if (datasync)
                 flags |= FSYNC_DATA;
+        if (VN_TRUNC(vp))
+                VUNTRUNCATE(vp);
         VOP_FSYNC(vp, flags, NULL, (xfs_off_t)0, (xfs_off_t)-1, error);
         return -error;
 }
@@ -578,6 +591,7 @@ const struct file_operations xfs_file_operations = {
 #endif
         .mmap           = xfs_file_mmap,
         .open           = xfs_file_open,
+        .flush          = xfs_file_close,
         .release        = xfs_file_release,
         .fsync          = xfs_file_fsync,
 #ifdef HAVE_FOP_OPEN_EXEC
@@ -602,6 +616,7 @@ const struct file_operations xfs_invis_file_operations = {
 #endif
         .mmap           = xfs_file_mmap,
         .open           = xfs_file_open,
+        .flush          = xfs_file_close,
         .release        = xfs_file_release,
         .fsync          = xfs_file_fsync,
 };
diff --git a/fs/xfs/linux-2.6/xfs_fs_subr.c b/fs/xfs/linux-2.6/xfs_fs_subr.c
index 575f2a790f31..f0c56daf4d6d 100644
--- a/fs/xfs/linux-2.6/xfs_fs_subr.c
+++ b/fs/xfs/linux-2.6/xfs_fs_subr.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
+ * Copyright (c) 2000-2002,2005-2006 Silicon Graphics, Inc.
  * All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or
@@ -15,40 +15,12 @@
  * along with this program; if not, write the Free Software Foundation,
  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
-
 #include "xfs.h"
 
-/*
- * Stub for no-op vnode operations that return error status.
- */
-int
-fs_noerr(void)
-{
-        return 0;
-}
+int  fs_noerr(void) { return 0; }
+int  fs_nosys(void) { return ENOSYS; }
+void fs_noval(void) { return; }
 
-/*
- * Operation unsupported under this file system.
- */
-int
-fs_nosys(void)
-{
-        return ENOSYS;
-}
-
-/*
- * Stub for inactive, strategy, and read/write lock/unlock.  Does nothing.
- */
-/* ARGSUSED */
-void
-fs_noval(void)
-{
-}
-
-/*
- * vnode pcache layer for vnode_tosspages.
- * 'last' parameter unused but left in for IRIX compatibility
- */
 void
 fs_tosspages(
         bhv_desc_t      *bdp,
@@ -63,11 +35,6 @@ fs_tosspages(
                 truncate_inode_pages(ip->i_mapping, first);
 }
 
-
-/*
- * vnode pcache layer for vnode_flushinval_pages.
- * 'last' parameter unused but left in for IRIX compatibility
- */
 void
 fs_flushinval_pages(
         bhv_desc_t      *bdp,
@@ -79,16 +46,13 @@ fs_flushinval_pages(
         struct inode    *ip = vn_to_inode(vp);
 
         if (VN_CACHED(vp)) {
+                if (VN_TRUNC(vp))
+                        VUNTRUNCATE(vp);
                 filemap_write_and_wait(ip->i_mapping);
-
                 truncate_inode_pages(ip->i_mapping, first);
         }
 }
 
-/*
- * vnode pcache layer for vnode_flush_pages.
- * 'last' parameter unused but left in for IRIX compatibility
- */
 int
 fs_flush_pages(
         bhv_desc_t      *bdp,
@@ -100,12 +64,13 @@ fs_flush_pages(
         vnode_t         *vp = BHV_TO_VNODE(bdp);
         struct inode    *ip = vn_to_inode(vp);
 
-        if (VN_CACHED(vp)) {
+        if (VN_DIRTY(vp)) {
+                if (VN_TRUNC(vp))
+                        VUNTRUNCATE(vp);
                 filemap_fdatawrite(ip->i_mapping);
                 if (flags & XFS_B_ASYNC)
                         return 0;
                 filemap_fdatawait(ip->i_mapping);
         }
-
         return 0;
 }
diff --git a/fs/xfs/linux-2.6/xfs_vnode.h b/fs/xfs/linux-2.6/xfs_vnode.h
index a64b7db67003..569a4e7b5cc1 100644
--- a/fs/xfs/linux-2.6/xfs_vnode.h
+++ b/fs/xfs/linux-2.6/xfs_vnode.h
@@ -56,12 +56,18 @@ typedef xfs_ino_t vnumber_t;
 typedef struct dentry vname_t;
 typedef bhv_head_t vn_bhv_head_t;
 
+typedef enum vflags {
+        VMODIFIED       = 0x08, /* XFS inode state possibly differs */
+                                /* to the Linux inode state. */
+        VTRUNCATED      = 0x40, /* truncated down so flush-on-close */
+} vflags_t;
+
 /*
  * MP locking protocols:
  *      v_flag, v_vfsp                          VN_LOCK/VN_UNLOCK
  */
 typedef struct vnode {
-        __u32           v_flag;                 /* vnode flags (see below) */
+        vflags_t        v_flag;                 /* vnode flags (see above) */
         struct vfs      *v_vfsp;                /* ptr to containing VFS */
         vnumber_t       v_number;               /* in-core vnode number */
         vn_bhv_head_t   v_bh;                   /* behavior head */
@@ -126,12 +132,6 @@ static inline struct inode *vn_to_inode(struct vnode *vnode)
 }
 
 /*
- * Vnode flags.
- */
-#define VMODIFIED              0x8      /* XFS inode state possibly differs */
-                                        /* to the Linux inode state.    */
-
-/*
  * Values for the VOP_RWLOCK and VOP_RWUNLOCK flags parameter.
  */
 typedef enum vrwlock {
@@ -162,8 +162,10 @@ typedef enum vchange {
         VCHANGE_FLAGS_IOEXCL_COUNT      = 4
 } vchange_t;
 
+typedef enum { L_FALSE, L_TRUE } lastclose_t;
 
 typedef int     (*vop_open_t)(bhv_desc_t *, struct cred *);
+typedef int     (*vop_close_t)(bhv_desc_t *, int, lastclose_t, struct cred *);
 typedef ssize_t (*vop_read_t)(bhv_desc_t *, struct kiocb *,
                                 const struct iovec *, unsigned int,
                                 loff_t *, int, struct cred *);
@@ -234,6 +236,7 @@ typedef int	(*vop_iflush_t)(bhv_desc_t *, int);
 typedef struct vnodeops {
         bhv_position_t  vn_position;    /* position within behavior chain */
         vop_open_t              vop_open;
+        vop_close_t             vop_close;
         vop_read_t              vop_read;
         vop_write_t             vop_write;
         vop_sendfile_t          vop_sendfile;
@@ -278,6 +281,10 @@ typedef struct vnodeops {
  */
 #define _VOP_(op, vp)   (*((vnodeops_t *)(vp)->v_fops)->op)
 
+#define VOP_OPEN(vp, cr, rv)                                            \
+        rv = _VOP_(vop_open, vp)((vp)->v_fbhv, cr)
+#define VOP_CLOSE(vp, f, last, cr, rv)                                  \
+        rv = _VOP_(vop_close, vp)((vp)->v_fbhv, f, last, cr)
 #define VOP_READ(vp,file,iov,segs,offset,ioflags,cr,rv)                 \
         rv = _VOP_(vop_read, vp)((vp)->v_fbhv,file,iov,segs,offset,ioflags,cr)
 #define VOP_WRITE(vp,file,iov,segs,offset,ioflags,cr,rv)                \
@@ -290,8 +297,6 @@ typedef struct vnodeops {
         rv = _VOP_(vop_splice_write, vp)((vp)->v_fbhv,f,o,pipe,cnt,fl,iofl,cr)
 #define VOP_BMAP(vp,of,sz,rw,b,n,rv)                                    \
         rv = _VOP_(vop_bmap, vp)((vp)->v_fbhv,of,sz,rw,b,n)
-#define VOP_OPEN(vp, cr, rv)                                            \
-        rv = _VOP_(vop_open, vp)((vp)->v_fbhv, cr)
 #define VOP_GETATTR(vp, vap, f, cr, rv)                                 \
         rv = _VOP_(vop_getattr, vp)((vp)->v_fbhv, vap, f, cr)
 #define VOP_SETATTR(vp, vap, f, cr, rv)                                 \
@@ -556,8 +561,6 @@ static inline struct vnode *vn_grab(struct vnode *vp)
  */
 #define VN_LOCK(vp)             mutex_spinlock(&(vp)->v_lock)
 #define VN_UNLOCK(vp, s)        mutex_spinunlock(&(vp)->v_lock, s)
-#define VN_FLAGSET(vp,b)        vn_flagset(vp,b)
-#define VN_FLAGCLR(vp,b)        vn_flagclr(vp,b)
 
 static __inline__ void vn_flagset(struct vnode *vp, uint flag)
 {
@@ -566,13 +569,22 @@ static __inline__ void vn_flagset(struct vnode *vp, uint flag)
         spin_unlock(&vp->v_lock);
 }
 
-static __inline__ void vn_flagclr(struct vnode *vp, uint flag)
+static __inline__ uint vn_flagclr(struct vnode *vp, uint flag)
 {
+        uint    cleared;
+
         spin_lock(&vp->v_lock);
+        cleared = (vp->v_flag & flag);
         vp->v_flag &= ~flag;
         spin_unlock(&vp->v_lock);
+        return cleared;
 }
 
+#define VMODIFY(vp)     vn_flagset(vp, VMODIFIED)
+#define VUNMODIFY(vp)   vn_flagclr(vp, VMODIFIED)
+#define VTRUNCATE(vp)   vn_flagset(vp, VTRUNCATED)
+#define VUNTRUNCATE(vp) vn_flagclr(vp, VTRUNCATED)
+
 /*
  * Dealing with bad inodes
  */
@@ -612,8 +624,7 @@ static inline void vn_atime_to_time_t(struct vnode *vp, time_t *tt)
 #define VN_CACHED(vp)   (vn_to_inode(vp)->i_mapping->nrpages)
 #define VN_DIRTY(vp)    mapping_tagged(vn_to_inode(vp)->i_mapping, \
                                         PAGECACHE_TAG_DIRTY)
-#define VMODIFY(vp)     VN_FLAGSET(vp, VMODIFIED)
-#define VUNMODIFY(vp)   VN_FLAGCLR(vp, VMODIFIED)
+#define VN_TRUNC(vp)    ((vp)->v_flag & VTRUNCATED)
 
 /*
  * Flags to VOP_SETATTR/VOP_GETATTR.
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index cb36a56392e7..35906bae92e1 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 @@ 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.
@@ -937,6 +955,13 @@ 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,