[PATCH 5.15 187/206] fuse: lock inode unconditionally in fuse_fallocate()

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Miklos Szeredi <mszeredi@xxxxxxxxxx>

commit 44361e8cf9ddb23f17bdcc40ca944abf32e83e79 upstream.

file_modified() must be called with inode lock held.  fuse_fallocate()
didn't lock the inode in case of just FALLOC_KEEP_SIZE flags value, which
resulted in a kernel Warning in notify_change().

Lock the inode unconditionally, like all other fallocate implementations
do.

Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Reported-and-tested-by: syzbot+462da39f0667b357c4b6@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 4a6f278d4827 ("fuse: add file_modified() to fallocate")
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/fuse/file.c |   41 ++++++++++++++++++-----------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2937,11 +2937,9 @@ static long fuse_file_fallocate(struct f
 		.mode = mode
 	};
 	int err;
-	bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
-			   (mode & (FALLOC_FL_PUNCH_HOLE |
-				    FALLOC_FL_ZERO_RANGE));
-
-	bool block_faults = FUSE_IS_DAX(inode) && lock_inode;
+	bool block_faults = FUSE_IS_DAX(inode) &&
+		(!(mode & FALLOC_FL_KEEP_SIZE) ||
+		 (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)));
 
 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
 		     FALLOC_FL_ZERO_RANGE))
@@ -2950,22 +2948,20 @@ static long fuse_file_fallocate(struct f
 	if (fm->fc->no_fallocate)
 		return -EOPNOTSUPP;
 
-	if (lock_inode) {
-		inode_lock(inode);
-		if (block_faults) {
-			filemap_invalidate_lock(inode->i_mapping);
-			err = fuse_dax_break_layouts(inode, 0, 0);
-			if (err)
-				goto out;
-		}
-
-		if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) {
-			loff_t endbyte = offset + length - 1;
-
-			err = fuse_writeback_range(inode, offset, endbyte);
-			if (err)
-				goto out;
-		}
+	inode_lock(inode);
+	if (block_faults) {
+		filemap_invalidate_lock(inode->i_mapping);
+		err = fuse_dax_break_layouts(inode, 0, 0);
+		if (err)
+			goto out;
+	}
+
+	if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) {
+		loff_t endbyte = offset + length - 1;
+
+		err = fuse_writeback_range(inode, offset, endbyte);
+		if (err)
+			goto out;
 	}
 
 	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
@@ -3015,8 +3011,7 @@ out:
 	if (block_faults)
 		filemap_invalidate_unlock(inode->i_mapping);
 
-	if (lock_inode)
-		inode_unlock(inode);
+	inode_unlock(inode);
 
 	fuse_flush_time_update(inode);