From: David Howells <dhowells@redhat.com>
To: linux-afs@lists.infradead.org
Cc: Jonathan Billings <jsbillings@jsbillings.org>,
dhowells@redhat.com, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 03/10] afs: Fix AFS file locking to allow fine grained locks
Date: Fri, 15 Mar 2019 22:59:42 +0000 [thread overview]
Message-ID: <155269078209.8537.15085378940532959137.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <155269076033.8537.10785090349210421514.stgit@warthog.procyon.org.uk>
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 | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)
diff --git a/fs/afs/flock.c b/fs/afs/flock.c
index 8b02f0056d54..6919f53ed4ad 100644
--- a/fs/afs/flock.c
+++ b/fs/afs/flock.c
@@ -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)
- fl->fl_type = F_RDLCK;
- else
- fl->fl_type = F_WRLCK;
- fl->fl_start = 0;
- fl->fl_end = OFFSET_MAX;
+ 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;
next prev parent reply other threads:[~2019-03-15 23:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-15 22:59 [PATCH 00/10] AFS fixes David Howells
2019-03-15 22:59 ` [PATCH 01/10] afs: Split wait from afs_make_call() David Howells
2019-03-15 22:59 ` [PATCH 02/10] afs: Calculate lock extend timer from set/extend reply reception David Howells
2019-03-15 22:59 ` David Howells [this message]
2019-03-15 22:59 ` [PATCH 04/10] afs: Further fix file locking David Howells
2019-03-15 22:59 ` [PATCH 05/10] afs: Add file locking tracepoints David Howells
2019-03-15 23:00 ` [PATCH 06/10] afs: Improve dir check failure reports David Howells
2019-03-15 23:00 ` [PATCH 07/10] afs: Handle lock rpc ops failing on a file that got deleted David Howells
2019-03-15 23:00 ` [PATCH 08/10] afs: Add directory reload tracepoint David Howells
2019-03-15 23:00 ` [PATCH 09/10] afs: Implement sillyrename for unlink and rename David Howells
2019-03-15 23:00 ` [PATCH 10/10] afs: Add more tracepoints David Howells
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