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由 Theodore Ts'o 提交于
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: NTheodore Ts'o <tytso@mit.edu>
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