linux/fs/9p
Tyler Hicks 2a3dcbccd6 9p: Fix refcounting during full path walks for fid lookups
Decrement the refcount of the parent dentry's fid after walking
each path component during a full path walk for a lookup. Failure to do
so can lead to fids that are not clunked until the filesystem is
unmounted, as indicated by this warning:

 9pnet: found fid 3 not clunked

The improper refcounting after walking resulted in open(2) returning
-EIO on any directories underneath the mount point when using the virtio
transport. When using the fd transport, there's no apparent issue until
the filesytem is unmounted and the warning above is emitted to the logs.

In some cases, the user may not yet be attached to the filesystem and a
new root fid, associated with the user, is created and attached to the
root dentry before the full path walk is performed. Increment the new
root fid's refcount to two in that situation so that it can be safely
decremented to one after it is used for the walk operation. The new fid
will still be attached to the root dentry when
v9fs_fid_lookup_with_uid() returns so a final refcount of one is
correct/expected.

Link: https://lkml.kernel.org/r/20220527000003.355812-2-tyhicks@linux.microsoft.com
Link: https://lkml.kernel.org/r/20220612085330.1451496-4-asmadeus@codewreck.org
Fixes: 6636b6dcc3 ("9p: add refcount to p9_fid struct")
Cc: stable@vger.kernel.org
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
[Dominique: fix clunking fid multiple times discussed in second link]
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
2022-06-15 12:05:33 +09:00
..
acl.c 9p: fix a bunch of checkpatch warnings 2021-11-04 21:04:25 +09:00
acl.h 9p: fix a bunch of checkpatch warnings 2021-11-04 21:04:25 +09:00
cache.c netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_context 2022-06-09 13:55:00 -07:00
cache.h 9p: Use fscache indexing rewrite and reenable caching 2022-01-10 11:53:06 +00:00
fid.c 9p: Fix refcounting during full path walks for fid lookups 2022-06-15 12:05:33 +09:00
fid.h 9p: apply review requests for fid refcounting 2020-11-19 17:21:34 +01:00
Kconfig 9p: Use fscache indexing rewrite and reenable caching 2022-01-10 11:53:06 +00:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
v9fs_vfs.h 9p: fix a bunch of checkpatch warnings 2021-11-04 21:04:25 +09:00
v9fs.c netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_context 2022-06-09 13:55:00 -07:00
v9fs.h netfs: Further cleanups after struct netfs_inode wrapper introduced 2022-06-10 20:55:21 +01:00
vfs_addr.c netfs: Rename the netfs_io_request cleanup op and give it an op pointer 2022-06-10 20:55:21 +01:00
vfs_dentry.c 9p: fix a bunch of checkpatch warnings 2021-11-04 21:04:25 +09:00
vfs_dir.c 9p: Use fscache indexing rewrite and reenable caching 2022-01-10 11:53:06 +00:00
vfs_file.c 9p-for-5.17-rc1: fixes, split 9p_net_fd, new reviewer 2022-01-16 07:36:49 +02:00
vfs_inode_dotl.c 9p: fix fid refcount leak in v9fs_vfs_atomic_open_dotl 2022-06-15 12:05:21 +09:00
vfs_inode.c 9p: fix fid refcount leak in v9fs_vfs_get_link 2022-06-15 12:05:29 +09:00
vfs_super.c 9p: Copy local writes to the cache when writing to the server 2022-01-10 11:53:25 +00:00
xattr.c 9p: fix file headers 2021-11-03 17:45:04 +09:00
xattr.h 9p: fix a bunch of checkpatch warnings 2021-11-04 21:04:25 +09:00