cifs_atomic_open(): fix double-put on late allocation failure (d9a9f484) · Commits · 戴 / test

several iterations of ->atomic_open() calling conventions ago, we used to need fput() if ->atomic_open() failed at some point after successful finish_open(). Now (since 2016) it's not needed - struct file carries enough state to make fput() work regardless of the point in struct file lifecycle and discarding it on failure exits in open() got unified. Unfortunately, I'd missed the fact that we had an instance of ->atomic_open() (cifs one) that used to need that fput(), as well as the stale comment in finish_open() demanding such late failure handling. Trivially fixed... Fixes: "do_last(): take fput() on error after opening to out:" Cc: stable@kernel.org # v4.7+ Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

Documentation/filesystems/porting.rst

+8 −0

Original line number	Diff line number	Diff line
		@@ -850,3 +850,11 @@ business doing so.
		d_alloc_pseudo() is internal-only; uses outside of alloc_file_pseudo() are
		very suspect (and won't work in modules). Such uses are very likely to
		be misspelled d_alloc_anon().

		---

		mandatory

		[should've been added in 2016] stale comment in finish_open() nonwithstanding,
		failure exits in ->atomic_open() instances should NOT fput() the file,
		no matter what. Everything is handled by the caller.

fs/cifs/dir.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -555,7 +555,6 @@ cifs_atomic_open(struct inode inode, struct dentry direntry,
		if (server->ops->close)
		server->ops->close(xid, tcon, &fid);
		cifs_del_pending_open(&open);
		fput(file);
		rc = -ENOMEM;
		}

fs/open.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -860,9 +860,6 @@ cleanup_file:
		* 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,

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