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author | Amir Goldstein <amir73il@gmail.com> | 2023-06-15 13:22:28 +0200 |
---|---|---|
committer | Christian Brauner <brauner@kernel.org> | 2023-06-19 18:16:38 +0200 |
commit | 62d53c4a1dfe347bd87ede46ffad38c9a3870338 (patch) | |
tree | 50bf37201de8a425c8e4cc23b1be69bde2e4b6eb /fs/open.c | |
parent | fs: move kmem_cache_zalloc() into alloc_empty_file*() helpers (diff) | |
download | linux-62d53c4a1dfe347bd87ede46ffad38c9a3870338.tar.xz linux-62d53c4a1dfe347bd87ede46ffad38c9a3870338.zip |
fs: use backing_file container for internal files with "fake" f_path
Overlayfs uses open_with_fake_path() to allocate internal kernel files,
with a "fake" path - whose f_path is not on the same fs as f_inode.
Allocate a container struct backing_file for those internal files, that
is used to hold the "fake" ovl path along with the real path.
backing_file_real_path() can be used to access the stored real path.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Message-Id: <20230615112229.2143178-5-amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/open.c')
-rw-r--r-- | fs/open.c | 45 |
1 files changed, 33 insertions, 12 deletions
diff --git a/fs/open.c b/fs/open.c index 322e017bf480..81186b277815 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1149,23 +1149,44 @@ struct file *kernel_file_open(const struct path *path, int flags, } EXPORT_SYMBOL_GPL(kernel_file_open); -struct file *open_with_fake_path(const struct path *path, int flags, - struct inode *inode, const struct cred *cred) +/** + * backing_file_open - open a backing file for kernel internal use + * @path: path of the file to open + * @flags: open flags + * @path: path of the backing file + * @cred: credentials for open + * + * Open a backing file for a stackable filesystem (e.g., overlayfs). + * @path may be on the stackable filesystem and backing inode on the + * underlying filesystem. In this case, we want to be able to return + * the @real_path of the backing inode. This is done by embedding the + * returned file into a container structure that also stores the path of + * the backing inode on the underlying filesystem, which can be + * retrieved using backing_file_real_path(). + */ +struct file *backing_file_open(const struct path *path, int flags, + const struct path *real_path, + const struct cred *cred) { - struct file *f = alloc_empty_file_noaccount(flags, cred); - if (!IS_ERR(f)) { - int error; + struct file *f; + int error; - f->f_path = *path; - error = do_dentry_open(f, inode, NULL); - if (error) { - fput(f); - f = ERR_PTR(error); - } + f = alloc_empty_backing_file(flags, cred); + if (IS_ERR(f)) + return f; + + f->f_path = *path; + path_get(real_path); + *backing_file_real_path(f) = *real_path; + error = do_dentry_open(f, d_inode(real_path->dentry), NULL); + if (error) { + fput(f); + f = ERR_PTR(error); } + return f; } -EXPORT_SYMBOL(open_with_fake_path); +EXPORT_SYMBOL_GPL(backing_file_open); #define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) #define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC) |