xfs: fix memory reclaim recursion deadlock on locked inode buffer

Calling into memory reclaim with a locked inode buffer can deadlock
if memory reclaim tries to lock the inode buffer during inode
teardown. Convert the relevant memory allocations to use KM_NOFS to
avoid this deadlock condition.

Reported-by: Peter Watkins <treestem@gmail.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_inode.c

@@ -422,7 +422,7 @@ xfs_iformat(
 	if (!XFS_DFORK_Q(dip))
 		return 0;
 	ASSERT(ip->i_afp == NULL);
-	ip->i_afp = kmem_zone_zalloc(xfs_ifork_zone, KM_SLEEP);
+	ip->i_afp = kmem_zone_zalloc(xfs_ifork_zone, KM_SLEEP | KM_NOFS);
 	ip->i_afp->if_ext_max =
 		XFS_IFORK_ASIZE(ip) / (uint)sizeof(xfs_bmbt_rec_t);
 	switch (dip->di_aformat) {
@@ -505,7 +505,7 @@ xfs_iformat_local(
 		ifp->if_u1.if_data = ifp->if_u2.if_inline_data;
 	else {
 		real_size = roundup(size, 4);
-		ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP);
+		ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP | KM_NOFS);
 	}
 	ifp->if_bytes = size;
 	ifp->if_real_bytes = real_size;
@@ -632,7 +632,7 @@ xfs_iformat_btree(
 	}
 
 	ifp->if_broot_bytes = size;
-	ifp->if_broot = kmem_alloc(size, KM_SLEEP);
+	ifp->if_broot = kmem_alloc(size, KM_SLEEP | KM_NOFS);
 	ASSERT(ifp->if_broot != NULL);
 	/*
 	 * Copy and convert from the on-disk structure
@@ -2191,7 +2191,7 @@ xfs_iroot_realloc(
 		 */
 		if (ifp->if_broot_bytes == 0) {
 			new_size = (size_t)XFS_BMAP_BROOT_SPACE_CALC(rec_diff);
-			ifp->if_broot = kmem_alloc(new_size, KM_SLEEP);
+			ifp->if_broot = kmem_alloc(new_size, KM_SLEEP | KM_NOFS);
 			ifp->if_broot_bytes = (int)new_size;
 			return;
 		}
@@ -2207,7 +2207,7 @@ xfs_iroot_realloc(
 		new_size = (size_t)XFS_BMAP_BROOT_SPACE_CALC(new_max);
 		ifp->if_broot = kmem_realloc(ifp->if_broot, new_size,
 				(size_t)XFS_BMAP_BROOT_SPACE_CALC(cur_max), /* old size */
-				KM_SLEEP);
+				KM_SLEEP | KM_NOFS);
 		op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
 						     ifp->if_broot_bytes);
 		np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
@@ -2233,7 +2233,7 @@ xfs_iroot_realloc(
 	else
 		new_size = 0;
 	if (new_size > 0) {
-		new_broot = kmem_alloc(new_size, KM_SLEEP);
+		new_broot = kmem_alloc(new_size, KM_SLEEP | KM_NOFS);
 		/*
 		 * First copy over the btree block header.
 		 */
@@ -2337,7 +2337,8 @@ xfs_idata_realloc(
 		real_size = roundup(new_size, 4);
 		if (ifp->if_u1.if_data == NULL) {
 			ASSERT(ifp->if_real_bytes == 0);
-			ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP);
+			ifp->if_u1.if_data = kmem_alloc(real_size,
+							KM_SLEEP | KM_NOFS);
 		} else if (ifp->if_u1.if_data != ifp->if_u2.if_inline_data) {
 			/*
 			 * Only do the realloc if the underlying size
@@ -2348,11 +2349,12 @@ xfs_idata_realloc(
 					kmem_realloc(ifp->if_u1.if_data,
 							real_size,
 							ifp->if_real_bytes,
-							KM_SLEEP);
+							KM_SLEEP | KM_NOFS);
 			}
 		} else {
 			ASSERT(ifp->if_real_bytes == 0);
-			ifp->if_u1.if_data = kmem_alloc(real_size, KM_SLEEP);
+			ifp->if_u1.if_data = kmem_alloc(real_size,
+							KM_SLEEP | KM_NOFS);
 			memcpy(ifp->if_u1.if_data, ifp->if_u2.if_inline_data,
 				ifp->if_bytes);
 		}