afs: Fix AFS file locking to allow fine grained locks (68ce801f) · Commits · 戴 / test

Fix AFS file locking to allow fine grained locks as some applications, such as firefox, won't work if they can't take such locks on certain state files - thereby preventing the use of kAFS to distribute a home directory. Note that this cannot be made completely functional as the protocol only has provision for whole-file locks, so there exists the possibility of a process deadlocking itself by getting a partial read-lock on a file first and then trying to get a non-overlapping write-lock - but we got the server's read lock with the first lock, so we're now stuck. OpenAFS solves this by just granting any partial-range lock directly without consulting the server - and hoping there's no remote collision. I want to implement that in a separate patch and it requires a bit more thought. Fixes: 8d6c554126b8 ("AFS: implement file locking") Reported-by:

Jonathan Billings <jsbillings@jsbillings.org> Signed-off-by:

David Howells <dhowells@redhat.com>

fs/afs/flock.c

+9 −14

Original line number	Diff line number	Diff line
		@@ -458,10 +458,6 @@ static int afs_do_setlk(struct file file, struct file_lock fl)

		_enter("{%llx:%llu},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);

		/* only whole-file locks are supported */
		if (fl->fl_start != 0 \|\| fl->fl_end != OFFSET_MAX)
		return -EINVAL;

		fl->fl_ops = &afs_lock_ops;
		INIT_LIST_HEAD(&fl->fl_u.afs.link);
		fl->fl_u.afs.state = AFS_LOCK_PENDING;
		@@ -613,10 +609,6 @@ static int afs_do_unlk(struct file file, struct file_lock fl)
		/* Flush all pending writes before doing anything with locks. */
		vfs_fsync(file, 0);

		/* only whole-file unlocks are supported */
		if (fl->fl_start != 0 \|\| fl->fl_end != OFFSET_MAX)
		return -EINVAL;

		ret = posix_lock_file(file, fl, NULL);
		_leave(" = %d [%u]", ret, vnode->lock_state);
		return ret;
		@@ -644,12 +636,15 @@ static int afs_do_getlk(struct file file, struct file_lock fl)
		goto error;

		lock_count = READ_ONCE(vnode->status.lock_count);
		if (lock_count != 0) {
		if (lock_count > 0)
		fl->fl_type = F_RDLCK;
		else
		fl->fl_type = F_WRLCK;
		fl->fl_start = 0;
		fl->fl_end = OFFSET_MAX;
		fl->fl_pid = 0;
		}
		}

		ret = 0;

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