]> Pileus Git - ~andy/linux/blobdiff - fs/xfs/xfs_inode.c
[XFS] Don't block pdflush when writing back inodes
[~andy/linux] / fs / xfs / xfs_inode.c
index 6f156faf9d46e3801e39b23bcab9d4b25e04dab2..3c3e9e3c1da81613e0b222650baab4797ddf10d9 100644 (file)
@@ -145,11 +145,16 @@ xfs_imap_to_bp(
        xfs_buf_t       *bp;
 
        error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, imap->im_blkno,
-                                  (int)imap->im_len, XFS_BUF_LOCK, &bp);
+                                  (int)imap->im_len, buf_flags, &bp);
        if (error) {
-               cmn_err(CE_WARN, "xfs_imap_to_bp: xfs_trans_read_buf()returned "
+               if (error != EAGAIN) {
+                       cmn_err(CE_WARN,
+                               "xfs_imap_to_bp: xfs_trans_read_buf()returned "
                                "an error %d on %s.  Returning error.",
                                error, mp->m_fsname);
+               } else {
+                       ASSERT(buf_flags & XFS_BUF_TRYLOCK);
+               }
                return error;
        }
 
@@ -274,7 +279,8 @@ xfs_itobp(
        xfs_dinode_t    **dipp,
        xfs_buf_t       **bpp,
        xfs_daddr_t     bno,
-       uint            imap_flags)
+       uint            imap_flags,
+       uint            buf_flags)
 {
        xfs_imap_t      imap;
        xfs_buf_t       *bp;
@@ -305,10 +311,17 @@ xfs_itobp(
        }
        ASSERT(bno == 0 || bno == imap.im_blkno);
 
-       error = xfs_imap_to_bp(mp, tp, &imap, &bp, XFS_BUF_LOCK, imap_flags);
+       error = xfs_imap_to_bp(mp, tp, &imap, &bp, buf_flags, imap_flags);
        if (error)
                return error;
 
+       if (!bp) {
+               ASSERT(buf_flags & XFS_BUF_TRYLOCK);
+               ASSERT(tp == NULL);
+               *bpp = NULL;
+               return EAGAIN;
+       }
+
        *dipp = (xfs_dinode_t *)xfs_buf_offset(bp, imap.im_boffset);
        *bpp = bp;
        return 0;
@@ -812,7 +825,7 @@ xfs_iread(
         * return NULL as well.  Set i_blkno to 0 so that xfs_itobp() will
         * know that this is a new incore inode.
         */
-       error = xfs_itobp(mp, tp, ip, &dip, &bp, bno, imap_flags);
+       error = xfs_itobp(mp, tp, ip, &dip, &bp, bno, imap_flags, XFS_BUF_LOCK);
        if (error) {
                kmem_zone_free(xfs_inode_zone, ip);
                return error;
@@ -1901,7 +1914,7 @@ xfs_iunlink(
                 * Here we put the head pointer into our next pointer,
                 * and then we fall through to point the head at us.
                 */
-               error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0);
+               error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
                if (error)
                        return error;
 
@@ -2009,7 +2022,7 @@ xfs_iunlink_remove(
                 * of dealing with the buffer when there is no need to
                 * change it.
                 */
-               error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0);
+               error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
                if (error) {
                        cmn_err(CE_WARN,
                                "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
@@ -2071,7 +2084,7 @@ xfs_iunlink_remove(
                 * Now last_ibp points to the buffer previous to us on
                 * the unlinked list.  Pull us from the list.
                 */
-               error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0);
+               error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
                if (error) {
                        cmn_err(CE_WARN,
                                "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
@@ -2334,7 +2347,7 @@ xfs_ifree(
 
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-       error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, 0, 0);
+       error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
        if (error)
                return error;
 
@@ -2777,38 +2790,41 @@ xfs_iunpin(
 }
 
 /*
- * This is called to wait for the given inode to be unpinned.
- * It will sleep until this happens.  The caller must have the
- * inode locked in at least shared mode so that the buffer cannot
- * be subsequently pinned once someone is waiting for it to be
- * unpinned.
+ * This is called to unpin an inode. It can be directed to wait or to return
+ * immediately without waiting for the inode to be unpinned.  The caller must
+ * have the inode locked in at least shared mode so that the buffer cannot be
+ * subsequently pinned once someone is waiting for it to be unpinned.
  */
 STATIC void
-xfs_iunpin_wait(
-       xfs_inode_t     *ip)
+__xfs_iunpin_wait(
+       xfs_inode_t     *ip,
+       int             wait)
 {
-       xfs_inode_log_item_t    *iip;
-       xfs_lsn_t       lsn;
+       xfs_inode_log_item_t    *iip = ip->i_itemp;
 
        ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE | MR_ACCESS));
-
-       if (atomic_read(&ip->i_pincount) == 0) {
+       if (atomic_read(&ip->i_pincount) == 0)
                return;
-       }
 
-       iip = ip->i_itemp;
-       if (iip && iip->ili_last_lsn) {
-               lsn = iip->ili_last_lsn;
-       } else {
-               lsn = (xfs_lsn_t)0;
-       }
+       /* Give the log a push to start the unpinning I/O */
+       xfs_log_force(ip->i_mount, (iip && iip->ili_last_lsn) ?
+                               iip->ili_last_lsn : 0, XFS_LOG_FORCE);
+       if (wait)
+               wait_event(ip->i_ipin_wait, (atomic_read(&ip->i_pincount) == 0));
+}
 
-       /*
-        * Give the log a push so we don't wait here too long.
-        */
-       xfs_log_force(ip->i_mount, lsn, XFS_LOG_FORCE);
+static inline void
+xfs_iunpin_wait(
+       xfs_inode_t     *ip)
+{
+       __xfs_iunpin_wait(ip, 1);
+}
 
-       wait_event(ip->i_ipin_wait, (atomic_read(&ip->i_pincount) == 0));
+static inline void
+xfs_iunpin_nowait(
+       xfs_inode_t     *ip)
+{
+       __xfs_iunpin_wait(ip, 0);
 }
 
 
@@ -3003,6 +3019,7 @@ xfs_iflush(
        int                     bufwasdelwri;
        struct hlist_node       *entry;
        enum { INT_DELWRI = (1 << 0), INT_ASYNC = (1 << 1) };
+       int                     noblock = (flags == XFS_IFLUSH_ASYNC_NOBLOCK);
 
        XFS_STATS_INC(xs_iflush_count);
 
@@ -3027,11 +3044,21 @@ xfs_iflush(
        }
 
        /*
-        * We can't flush the inode until it is unpinned, so
-        * wait for it.  We know noone new can pin it, because
-        * we are holding the inode lock shared and you need
-        * to hold it exclusively to pin the inode.
+        * We can't flush the inode until it is unpinned, so wait for it if we
+        * are allowed to block.  We know noone new can pin it, because we are
+        * holding the inode lock shared and you need to hold it exclusively to
+        * pin the inode.
+        *
+        * If we are not allowed to block, force the log out asynchronously so
+        * that when we come back the inode will be unpinned. If other inodes
+        * in the same cluster are dirty, they will probably write the inode
+        * out for us if they occur after the log force completes.
         */
+       if (noblock && xfs_ipincount(ip)) {
+               xfs_iunpin_nowait(ip);
+               xfs_ifunlock(ip);
+               return EAGAIN;
+       }
        xfs_iunpin_wait(ip);
 
        /*
@@ -3047,15 +3074,6 @@ xfs_iflush(
                return XFS_ERROR(EIO);
        }
 
-       /*
-        * Get the buffer containing the on-disk inode.
-        */
-       error = xfs_itobp(mp, NULL, ip, &dip, &bp, 0, 0);
-       if (error) {
-               xfs_ifunlock(ip);
-               return error;
-       }
-
        /*
         * Decide how buffer will be flushed out.  This is done before
         * the call to xfs_iflush_int because this field is zeroed by it.
@@ -3072,6 +3090,7 @@ xfs_iflush(
                case XFS_IFLUSH_DELWRI_ELSE_SYNC:
                        flags = 0;
                        break;
+               case XFS_IFLUSH_ASYNC_NOBLOCK:
                case XFS_IFLUSH_ASYNC:
                case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
                        flags = INT_ASYNC;
@@ -3091,6 +3110,7 @@ xfs_iflush(
                case XFS_IFLUSH_DELWRI:
                        flags = INT_DELWRI;
                        break;
+               case XFS_IFLUSH_ASYNC_NOBLOCK:
                case XFS_IFLUSH_ASYNC:
                        flags = INT_ASYNC;
                        break;
@@ -3104,6 +3124,16 @@ xfs_iflush(
                }
        }
 
+       /*
+        * Get the buffer containing the on-disk inode.
+        */
+       error = xfs_itobp(mp, NULL, ip, &dip, &bp, 0, 0,
+                               noblock ? XFS_BUF_TRYLOCK : XFS_BUF_LOCK);
+       if (error || !bp) {
+               xfs_ifunlock(ip);
+               return error;
+       }
+
        /*
         * First flush out the inode that xfs_iflush was called with.
         */
@@ -3112,6 +3142,13 @@ xfs_iflush(
                goto corrupt_out;
        }
 
+       /*
+        * If the buffer is pinned then push on the log now so we won't
+        * get stuck waiting in the write for too long.
+        */
+       if (XFS_BUF_ISPINNED(bp))
+               xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
+
        /*
         * inode clustering:
         * see if other inodes can be gathered into this write
@@ -3181,14 +3218,6 @@ xfs_iflush(
                XFS_STATS_ADD(xs_icluster_flushinode, clcount);
        }
 
-       /*
-        * If the buffer is pinned then push on the log so we won't
-        * get stuck waiting in the write for too long.
-        */
-       if (XFS_BUF_ISPINNED(bp)){
-               xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
-       }
-
        if (flags & INT_DELWRI) {
                xfs_bdwrite(mp, bp);
        } else if (flags & INT_ASYNC) {