[XFS] Stack footprint reduction for xfs_swapext (used from xfs_fsr)

SGI-PV: 913332
SGI-Modid: xfs-linux:xfs-kern:198926a

Signed-off-by: Eric Sandeen <sandeen@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>

diff --git a/fs/xfs/xfs_dfrag.c b/fs/xfs/xfs_dfrag.c
index 681be5c..8dd7a39 100644 (file)
--- a/fs/xfs/xfs_dfrag.c
+++ b/fs/xfs/xfs_dfrag.c
@@ -65,9 +65,9 @@
  */
 int
 xfs_swapext(
-       xfs_swapext_t   __user *sxp)
+       xfs_swapext_t   __user *sxu)
 {
-       xfs_swapext_t   sx;
+       xfs_swapext_t   *sxp;
        xfs_inode_t     *ip=NULL, *tip=NULL, *ips[2];
        xfs_trans_t     *tp;
        xfs_mount_t     *mp;
@@ -76,20 +76,29 @@ xfs_swapext(
        vnode_t         *vp, *tvp;
        bhv_desc_t      *bdp, *tbdp;
        vn_bhv_head_t   *bhp, *tbhp;
-       uint            lock_flags=0;
+       static uint     lock_flags = XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL;
        int             ilf_fields, tilf_fields;
        int             error = 0;
-       xfs_ifork_t     tempif, *ifp, *tifp;
+       xfs_ifork_t     *tempifp, *ifp, *tifp;
        __uint64_t      tmp;
        int             aforkblks = 0;
        int             taforkblks = 0;
-       int             locked = 0;
+       char            locked = 0;
 
-       if (copy_from_user(&sx, sxp, sizeof(sx)))
-               return XFS_ERROR(EFAULT);
+       sxp = kmem_alloc(sizeof(xfs_swapext_t), KM_MAYFAIL);
+       tempifp = kmem_alloc(sizeof(xfs_ifork_t), KM_MAYFAIL);
+       if (!sxp || !tempifp) {
+               error = XFS_ERROR(ENOMEM);
+               goto error0;
+       }
+
+       if (copy_from_user(sxp, sxu, sizeof(xfs_swapext_t))) {
+               error = XFS_ERROR(EFAULT);
+               goto error0;
+       }
 
        /* Pull information for the target fd */
-       if (((fp = fget((int)sx.sx_fdtarget)) == NULL) ||
+       if (((fp = fget((int)sxp->sx_fdtarget)) == NULL) ||
            ((vp = LINVFS_GET_VP(fp->f_dentry->d_inode)) == NULL))  {
                error = XFS_ERROR(EINVAL);
                goto error0;
@@ -104,7 +113,7 @@ xfs_swapext(
                ip = XFS_BHVTOI(bdp);
        }
 
-       if (((tfp = fget((int)sx.sx_fdtmp)) == NULL) ||
+       if (((tfp = fget((int)sxp->sx_fdtmp)) == NULL) ||
            ((tvp = LINVFS_GET_VP(tfp->f_dentry->d_inode)) == NULL)) {
                error = XFS_ERROR(EINVAL);
                goto error0;
@@ -131,7 +140,7 @@ xfs_swapext(
 
        mp = ip->i_mount;
 
-       sbp = &sx.sx_stat;
+       sbp = &sxp->sx_stat;
 
        if (XFS_FORCED_SHUTDOWN(mp)) {
                error =  XFS_ERROR(EIO);
@@ -148,7 +157,7 @@ xfs_swapext(
                ips[0] = tip;
                ips[1] = ip;
        }
-       lock_flags = XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL;
+
        xfs_lock_inodes(ips, 2, 0, lock_flags);
 
        /* Check permissions */
@@ -192,9 +201,9 @@ xfs_swapext(
        }
 
        /* Verify all data are being swapped */
-       if (sx.sx_offset != 0 ||
-           sx.sx_length != ip->i_d.di_size ||
-           sx.sx_length != tip->i_d.di_size) {
+       if (sxp->sx_offset != 0 ||
+           sxp->sx_length != ip->i_d.di_size ||
+           sxp->sx_length != tip->i_d.di_size) {
                error = XFS_ERROR(EFAULT);
                goto error0;
        }
@@ -255,7 +264,8 @@ xfs_swapext(
                xfs_iunlock(ip,  XFS_IOLOCK_EXCL);
                xfs_iunlock(tip, XFS_IOLOCK_EXCL);
                xfs_trans_cancel(tp, 0);
-               return error;
+               locked = 0;
+               goto error0;
        }
        xfs_lock_inodes(ips, 2, 0, XFS_ILOCK_EXCL);
 
@@ -266,10 +276,8 @@ xfs_swapext(
             (ip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)) {
                error = xfs_bmap_count_blocks(tp, ip, XFS_ATTR_FORK, &aforkblks);
                if (error) {
-                       xfs_iunlock(ip,  lock_flags);
-                       xfs_iunlock(tip, lock_flags);
                        xfs_trans_cancel(tp, 0);
-                       return error;
+                       goto error0;
                }
        }
        if ( ((XFS_IFORK_Q(tip) != 0) && (tip->i_d.di_anextents > 0)) &&
@@ -277,10 +285,8 @@ xfs_swapext(
                error = xfs_bmap_count_blocks(tp, tip, XFS_ATTR_FORK,
                        &taforkblks);
                if (error) {
-                       xfs_iunlock(ip,  lock_flags);
-                       xfs_iunlock(tip, lock_flags);
                        xfs_trans_cancel(tp, 0);
-                       return error;
+                       goto error0;
                }
        }
 
@@ -289,9 +295,9 @@ xfs_swapext(
         */
        ifp = &ip->i_df;
        tifp = &tip->i_df;
-       tempif = *ifp;  /* struct copy */
-       *ifp = *tifp;   /* struct copy */
-       *tifp = tempif; /* struct copy */
+       *tempifp = *ifp;        /* struct copy */
+       *ifp = *tifp;           /* struct copy */
+       *tifp = *tempifp;       /* struct copy */
 
        /*
         * Fix the on-disk inode values
@@ -369,11 +375,7 @@ xfs_swapext(
        }
 
        error = xfs_trans_commit(tp, XFS_TRANS_SWAPEXT, NULL);
-
-       fput(fp);
-       fput(tfp);
-
-       return error;
+       locked = 0;
 
  error0:
        if (locked) {
@@ -381,8 +383,15 @@ xfs_swapext(
                xfs_iunlock(tip, lock_flags);
        }
 
-       if (fp != NULL) fput(fp);
-       if (tfp != NULL) fput(tfp);
+       if (fp != NULL)
+               fput(fp);
+       if (tfp != NULL)
+               fput(tfp);
+
+       if (sxp != NULL)
+               kmem_free(sxp, sizeof(xfs_swapext_t));
+       if (tempifp != NULL)
+               kmem_free(tempifp, sizeof(xfs_ifork_t));
 
        return error;
 }