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| author | Miklos Szeredi <mszeredi@suse.cz> | 2013-09-16 14:51:55 +0200 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2013-09-16 19:17:24 -0400 |
| commit | 0854d450e229e37102a76e3ccf065d8e8137846f (patch) | |
| tree | 22fa987c0c2d6f8fbf1e89504ab044a7bab7d7ed /fs/open.c | |
| parent | 606035e76e79b14bf7a7c219140c045a952cc76e (diff) | |
| download | lwn-0854d450e229e37102a76e3ccf065d8e8137846f.tar.gz lwn-0854d450e229e37102a76e3ccf065d8e8137846f.zip | |
vfs: improve i_op->atomic_open() documentation
Fix documentation of ->atomic_open() and related functions: finish_open()
and finish_no_open(). Also add details that seem to be unclear and a
source of bugs (some of which are fixed in the following series).
Cc-ing maintainers of all filesystems implementing ->atomic_open().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Steve French <sfrench@samba.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/open.c')
| -rw-r--r-- | fs/open.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/fs/open.c b/fs/open.c index 2a731b0d08bc..d420331ca32a 100644 --- a/fs/open.c +++ b/fs/open.c @@ -744,14 +744,24 @@ cleanup_file: /** * finish_open - finish opening a file - * @od: opaque open data + * @file: file pointer * @dentry: pointer to dentry * @open: open callback + * @opened: state of open * * This can be used to finish opening a file passed to i_op->atomic_open(). * * If the open callback is set to NULL, then the standard f_op->open() * filesystem callback is substituted. + * + * NB: the dentry reference is _not_ consumed. If, for example, the dentry is + * the return value of d_splice_alias(), then the caller needs to perform dput() + * on it after finish_open(). + * + * On successful return @file is a fully instantiated open file. After this, if + * an error occurs in ->atomic_open(), it needs to clean up with fput(). + * + * Returns zero on success or -errno if the open failed. */ int finish_open(struct file *file, struct dentry *dentry, int (*open)(struct inode *, struct file *), @@ -772,11 +782,16 @@ EXPORT_SYMBOL(finish_open); /** * finish_no_open - finish ->atomic_open() without opening the file * - * @od: opaque open data + * @file: file pointer * @dentry: dentry or NULL (as returned from ->lookup()) * * This can be used to set the result of a successful lookup in ->atomic_open(). - * The filesystem's atomic_open() method shall return NULL after calling this. + * + * NB: unlike finish_open() this function does consume the dentry reference and + * the caller need not dput() it. + * + * Returns "1" which must be the return value of ->atomic_open() after having + * called this function. */ int finish_no_open(struct file *file, struct dentry *dentry) { |