aboutsummaryrefslogtreecommitdiff
path: root/fs/open.c
diff options
context:
space:
mode:
authorMiklos Szeredi <mszeredi@suse.cz>2013-09-16 14:51:55 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2013-09-16 19:17:24 -0400
commit0854d450e229e37102a76e3ccf065d8e8137846f (patch)
tree22fa987c0c2d6f8fbf1e89504ab044a7bab7d7ed /fs/open.c
parent606035e76e79b14bf7a7c219140c045a952cc76e (diff)
downloadlinux-linaro-stable-0854d450e229e37102a76e3ccf065d8e8137846f.tar.gz
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.c21
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)
{