From 705912ca95f4bbdbb3be753e46bf30d6be15a5e8 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 1 Sep 2014 14:34:09 -0400 Subject: ext4: teach ext4_ext_find_extent() to free path on error Right now, there are a places where it is all to easy to leak memory on an error path, via a usage like this: struct ext4_ext_path *path = NULL while (...) { ... path = ext4_ext_find_extent(inode, block, path, 0); if (IS_ERR(path)) { /* oops, if path was non-NULL before the call to ext4_ext_find_extent, we've leaked it! :-( */ ... return PTR_ERR(path); } ... } Unfortunately, there some code paths where we are doing the following instead: path = ext4_ext_find_extent(inode, block, orig_path, 0); and where it's important that we _not_ free orig_path in the case where ext4_ext_find_extent() returns an error. So change the function signature of ext4_ext_find_extent() so that it takes a struct ext4_ext_path ** for its third argument, and by default, on an error, it will free the struct ext4_ext_path, and then zero out the struct ext4_ext_path * pointer. In order to avoid causing problems, we add a flag EXT4_EX_NOFREE_ON_ERR which causes ext4_ext_find_extent() to use the original behavior of forcing the caller to deal with freeing the original path pointer on the error case. The goal is to get rid of EXT4_EX_NOFREE_ON_ERR entirely, but this allows for a gentle transition and makes the patches easier to verify. Signed-off-by: Theodore Ts'o --- fs/ext4/ext4.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/ext4/ext4.h') diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 550b4f99a843..696e51ae02fa 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -582,6 +582,7 @@ enum { */ #define EXT4_EX_NOCACHE 0x0800 #define EXT4_EX_FORCE_CACHE 0x1000 +#define EXT4_EX_NOFREE_ON_ERR 0x2000 /* * Flags used by ext4_free_blocks @@ -2733,7 +2734,7 @@ extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int); extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t, - struct ext4_ext_path *, + struct ext4_ext_path **, int flags); extern void ext4_ext_drop_refs(struct ext4_ext_path *); extern int ext4_ext_check_inode(struct inode *inode); -- cgit v1.2.1