[PATCH 5.10 008/147] gfs2: Add new gfs2_iomap_get helper

[Sasha Levin <sashal@kernel.org>]

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit 54992257fe4bb9f76f66b3863492aa8cc5567790 ]

Rename the current gfs2_iomap_get and gfs2_iomap_alloc functions to __*.
Add a new gfs2_iomap_get helper that doesn't expose struct metapath.
Rename gfs2_iomap_get_alloc to gfs2_iomap_alloc.  Use the new helpers
where they make sense.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Stable-dep-of: faddeb848305 ("gfs2: Fix use-after-free in iomap inline data write path")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/bmap.c | 65 +++++++++++++++++++++++++++-----------------------
 fs/gfs2/bmap.h |  6 +++--
 fs/gfs2/file.c |  5 ++--
 3 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 3d60ad9982c87..8ec1114ab452c 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -629,7 +629,7 @@ enum alloc_state {
 };
 
 /**
- * gfs2_iomap_alloc - Build a metadata tree of the requested height
+ * __gfs2_iomap_alloc - Build a metadata tree of the requested height
  * @inode: The GFS2 inode
  * @iomap: The iomap structure
  * @mp: The metapath, with proper height information calculated
@@ -639,7 +639,7 @@ enum alloc_state {
  *  ii) Indirect blocks to fill in lower part of the metadata tree
  * iii) Data blocks
  *
- * This function is called after gfs2_iomap_get, which works out the
+ * This function is called after __gfs2_iomap_get, which works out the
  * total number of blocks which we need via gfs2_alloc_size.
  *
  * We then do the actual allocation asking for an extent at a time (if
@@ -657,8 +657,8 @@ enum alloc_state {
  * Returns: errno on error
  */
 
-static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
-			    struct metapath *mp)
+static int __gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
+			      struct metapath *mp)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
@@ -799,10 +799,10 @@ static u64 gfs2_alloc_size(struct inode *inode, struct metapath *mp, u64 size)
 
 	/*
 	 * For writes to stuffed files, this function is called twice via
-	 * gfs2_iomap_get, before and after unstuffing. The size we return the
+	 * __gfs2_iomap_get, before and after unstuffing. The size we return the
 	 * first time needs to be large enough to get the reservation and
 	 * allocation sizes right.  The size we return the second time must
-	 * be exact or else gfs2_iomap_alloc won't do the right thing.
+	 * be exact or else __gfs2_iomap_alloc won't do the right thing.
 	 */
 
 	if (gfs2_is_stuffed(ip) || mp->mp_fheight != mp->mp_aheight) {
@@ -826,7 +826,7 @@ static u64 gfs2_alloc_size(struct inode *inode, struct metapath *mp, u64 size)
 }
 
 /**
- * gfs2_iomap_get - Map blocks from an inode to disk blocks
+ * __gfs2_iomap_get - Map blocks from an inode to disk blocks
  * @inode: The inode
  * @pos: Starting position in bytes
  * @length: Length to map, in bytes
@@ -836,9 +836,9 @@ static u64 gfs2_alloc_size(struct inode *inode, struct metapath *mp, u64 size)
  *
  * Returns: errno
  */
-static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
-			  unsigned flags, struct iomap *iomap,
-			  struct metapath *mp)
+static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
+			    unsigned flags, struct iomap *iomap,
+			    struct metapath *mp)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
@@ -972,12 +972,10 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
 int gfs2_lblk_to_dblk(struct inode *inode, u32 lblock, u64 *dblock)
 {
 	struct iomap iomap = { };
-	struct metapath mp = { .mp_aheight = 1, };
 	loff_t pos = (loff_t)lblock << inode->i_blkbits;
 	int ret;
 
-	ret = gfs2_iomap_get(inode, pos, i_blocksize(inode), 0, &iomap, &mp);
-	release_metapath(&mp);
+	ret = gfs2_iomap_get(inode, pos, i_blocksize(inode), &iomap);
 	if (ret == 0)
 		*dblock = iomap.addr >> inode->i_blkbits;
 
@@ -1106,14 +1104,14 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 			if (ret)
 				goto out_trans_end;
 			release_metapath(mp);
-			ret = gfs2_iomap_get(inode, iomap->offset,
-					     iomap->length, flags, iomap, mp);
+			ret = __gfs2_iomap_get(inode, iomap->offset,
+					       iomap->length, flags, iomap, mp);
 			if (ret)
 				goto out_trans_end;
 		}
 
 		if (iomap->type == IOMAP_HOLE) {
-			ret = gfs2_iomap_alloc(inode, iomap, mp);
+			ret = __gfs2_iomap_alloc(inode, iomap, mp);
 			if (ret) {
 				gfs2_trans_end(sdp);
 				gfs2_inplace_release(ip);
@@ -1165,7 +1163,7 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
 			goto out;
 	}
 
-	ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
+	ret = __gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
 	if (ret)
 		goto out_unlock;
 
@@ -1286,9 +1284,7 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
 	struct gfs2_inode *ip = GFS2_I(inode);
 	loff_t pos = (loff_t)lblock << inode->i_blkbits;
 	loff_t length = bh_map->b_size;
-	struct metapath mp = { .mp_aheight = 1, };
 	struct iomap iomap = { };
-	int flags = create ? IOMAP_WRITE : 0;
 	int ret;
 
 	clear_buffer_mapped(bh_map);
@@ -1296,10 +1292,10 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
 	clear_buffer_boundary(bh_map);
 	trace_gfs2_bmap(ip, bh_map, lblock, create, 1);
 
-	ret = gfs2_iomap_get(inode, pos, length, flags, &iomap, &mp);
-	if (create && !ret && iomap.type == IOMAP_HOLE)
-		ret = gfs2_iomap_alloc(inode, &iomap, &mp);
-	release_metapath(&mp);
+	if (!create)
+		ret = gfs2_iomap_get(inode, pos, length, &iomap);
+	else
+		ret = gfs2_iomap_alloc(inode, pos, length, &iomap);
 	if (ret)
 		goto out;
 
@@ -1457,15 +1453,26 @@ static int trunc_start(struct inode *inode, u64 newsize)
 	return error;
 }
 
-int gfs2_iomap_get_alloc(struct inode *inode, loff_t pos, loff_t length,
-			 struct iomap *iomap)
+int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
+		   struct iomap *iomap)
+{
+	struct metapath mp = { .mp_aheight = 1, };
+	int ret;
+
+	ret = __gfs2_iomap_get(inode, pos, length, 0, iomap, &mp);
+	release_metapath(&mp);
+	return ret;
+}
+
+int gfs2_iomap_alloc(struct inode *inode, loff_t pos, loff_t length,
+		     struct iomap *iomap)
 {
 	struct metapath mp = { .mp_aheight = 1, };
 	int ret;
 
-	ret = gfs2_iomap_get(inode, pos, length, IOMAP_WRITE, iomap, &mp);
+	ret = __gfs2_iomap_get(inode, pos, length, IOMAP_WRITE, iomap, &mp);
 	if (!ret && iomap->type == IOMAP_HOLE)
-		ret = gfs2_iomap_alloc(inode, iomap, &mp);
+		ret = __gfs2_iomap_alloc(inode, iomap, &mp);
 	release_metapath(&mp);
 	return ret;
 }
@@ -2516,7 +2523,6 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
 static int gfs2_map_blocks(struct iomap_writepage_ctx *wpc, struct inode *inode,
 		loff_t offset)
 {
-	struct metapath mp = { .mp_aheight = 1, };
 	int ret;
 
 	if (WARN_ON_ONCE(gfs2_is_stuffed(GFS2_I(inode))))
@@ -2527,8 +2533,7 @@ static int gfs2_map_blocks(struct iomap_writepage_ctx *wpc, struct inode *inode,
 		return 0;
 
 	memset(&wpc->iomap, 0, sizeof(wpc->iomap));
-	ret = gfs2_iomap_get(inode, offset, INT_MAX, 0, &wpc->iomap, &mp);
-	release_metapath(&mp);
+	ret = gfs2_iomap_get(inode, offset, INT_MAX, &wpc->iomap);
 	return ret;
 }
 
diff --git a/fs/gfs2/bmap.h b/fs/gfs2/bmap.h
index aed4632d47d30..c63efee8aaa43 100644
--- a/fs/gfs2/bmap.h
+++ b/fs/gfs2/bmap.h
@@ -49,8 +49,10 @@ extern const struct iomap_writeback_ops gfs2_writeback_ops;
 extern int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page);
 extern int gfs2_block_map(struct inode *inode, sector_t lblock,
 			  struct buffer_head *bh, int create);
-extern int gfs2_iomap_get_alloc(struct inode *inode, loff_t pos, loff_t length,
-				struct iomap *iomap);
+extern int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
+			  struct iomap *iomap);
+extern int gfs2_iomap_alloc(struct inode *inode, loff_t pos, loff_t length,
+			    struct iomap *iomap);
 extern int gfs2_extent_map(struct inode *inode, u64 lblock, int *new,
 			   u64 *dblock, unsigned *extlen);
 extern int gfs2_setattr_size(struct inode *inode, u64 size);
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 5e2fe456ed922..ec5000e13bb70 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -422,7 +422,7 @@ static int gfs2_allocate_page_backing(struct page *page, unsigned int length)
 	do {
 		struct iomap iomap = { };
 
-		if (gfs2_iomap_get_alloc(page->mapping->host, pos, length, &iomap))
+		if (gfs2_iomap_alloc(page->mapping->host, pos, length, &iomap))
 			return -EIO;
 
 		if (length < iomap.length)
@@ -1001,8 +1001,7 @@ static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
 	while (offset < end) {
 		struct iomap iomap = { };
 
-		error = gfs2_iomap_get_alloc(inode, offset, end - offset,
-					     &iomap);
+		error = gfs2_iomap_alloc(inode, offset, end - offset, &iomap);
 		if (error)
 			goto out;
 		offset = iomap.offset + iomap.length;
-- 
2.51.0