diff options
| -rw-r--r-- | fs/namei.c | 43 |
1 files changed, 24 insertions, 19 deletions
diff --git a/fs/namei.c b/fs/namei.c index 6db5b7e8547b..c0da9b5dd47a 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4337,8 +4337,7 @@ static int may_o_create(struct mnt_idmap *idmap, } /** - * atomic_open() - attempt to atomically look up, create and open a file - * from a negative dentry. + * atomic_open() - atomically look up, create and open a file * @path: parent directory path * @dentry: child to ->atomic_open() * @file: file to attach child to @@ -4346,6 +4345,9 @@ static int may_o_create(struct mnt_idmap *idmap, * @mode: create mode * @create_error: return value from may_o_create() * + * Attempt to look up, create and open @dentry, which must be negative, in a + * single call into the filesystem. + * * If a non-error dentry is returned then: when FMODE_OPENED is set, * the file will have been attached to @file by the filesystem calling * finish_open(). If FMODE_OPENED isn't set, the filesystem instead called @@ -4354,8 +4356,8 @@ static int may_o_create(struct mnt_idmap *idmap, * FMODE_CREATED is set when the call to ->atomic_open() actually created * the file. * - * Returns the opened/looked-up dentry on success or ERR_PTR(-E) on failure. - * On error, atomic_open() consumes @dentry. + * Returns: the opened or looked-up dentry, or ERR_PTR() on failure. The + * reference to @dentry is consumed in either case. */ static struct dentry *atomic_open(const struct path *path, struct dentry *dentry, struct file *file, @@ -4375,6 +4377,7 @@ static struct dentry *atomic_open(const struct path *path, struct dentry *dentry if (file->f_mode & FMODE_OPENED) { /* finish_open() called */ struct dentry *opened = file->f_path.dentry; + if (unlikely(opened != dentry)) { dput(dentry); dentry = dget(opened); @@ -4382,6 +4385,7 @@ static struct dentry *atomic_open(const struct path *path, struct dentry *dentry } else if (likely(file->f_path.dentry != DENTRY_NOT_SET)) { /* finish_no_open() called */ struct dentry *replaced = file->f_path.dentry; + if (replaced) { dput(dentry); dentry = replaced; @@ -4390,8 +4394,9 @@ static struct dentry *atomic_open(const struct path *path, struct dentry *dentry error = -ENOENT; } else { const char *fsname = dentry->d_sb->s_type->name; + WARN(1, "%s: ->atomic_open() left file->f_path.dentry unset!\n", - fsname); + fsname); error = -EIO; } } @@ -4417,17 +4422,16 @@ static struct dentry *atomic_open(const struct path *path, struct dentry *dentry /* * Look up and maybe create and open the last component. * - * Must be called with parent locked (exclusive in O_CREAT case). + * Takes the parent inode lock itself, exclusive if O_CREAT was requested and + * shared otherwise, and drops it again before returning. The caller must not + * hold it. * - * Returns 0 on success, that is, if - * the file was successfully atomically created (if necessary) and opened, or - * the file was not completely opened at this time, though lookups and - * creations were performed. - * These case are distinguished by presence of FMODE_OPENED on file->f_mode. - * In the latter case dentry returned in @path might be negative if O_CREAT - * hadn't been specified. + * On success returns the dentry of the last component. If FMODE_OPENED is set + * on file->f_mode the file was also opened and attached to @file; otherwise + * only lookup and creation were performed and the caller has to open it. In + * the latter case the dentry may be negative if O_CREAT hadn't been specified. * - * An error code is returned on failure. + * Returns ERR_PTR() on failure. */ static struct dentry *lookup_open(struct nameidata *nd, struct file *file, const struct open_flags *op) @@ -4452,8 +4456,7 @@ retry: got_write = !mnt_want_write(nd->path.mnt); /* * do _not_ fail yet - we might not need that or fail with - * a different error; let lookup_open() decide; we'll be - * dropping this one anyway. + * a different error; we'll be dropping this one anyway. */ } if (open_flag & O_CREAT) @@ -4540,8 +4543,10 @@ retry: } } if (dentry->d_inode || !(op->open_flag & O_CREAT)) { - /* No need to create a file. If lookup returned a positive - * dentry, the file will be opened in do_open(). */ + /* + * No need to create a file. If lookup returned a positive + * dentry, the file will be opened in do_open(). + */ goto out; } @@ -4607,7 +4612,7 @@ out_dput: * @mode: initial permissions for file * * Open a file after lookup and/or create. This provides similar - * functionality open_last_lookups() for non-VFS users, particularly + * functionality to open_last_lookups() for non-VFS users, particularly * nfsd. * It uses ->atomic_open or ->lookup / ->create / ->open as appropriate. * |