When looking at performance issues around directory caching, or debugging
directory lease issues, it is helpful to be able to display the current
directory leases (as we can e.g. or open files). Create pseudo-file
/proc/fs/cifs/open_dirs that displays current directory leases. Here
is sample output:
cat /proc/fs/cifs/open_dirs
Version:1
Format:
<tree id> <sess id> <persistent fid> <path>
Num entries: 3
0xce4c1c68 0x7176aa54 0xd95ef58e \dira valid file info, valid dirents
0xce4c1c68 0x7176aa54 0xd031e211 \dir5 valid file info, valid dirents
0xce4c1c68 0x7176aa54 0x96533a90 \dir1 valid file info
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The handlecache code today tracks the time at which dir lease was
acquired and the laundromat thread uses that to check for old
entries to cleanup.
However, if a directory is actively accessed, it should not
be chosen to expire first.
This change adds a new last_access_time field to cfid and
uses that to decide expiry of the cfid.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
cached_dir_lease_break() has return type as int but only
returning true or false. change return type of this function
to bool for clarity.
Signed-off-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Change the pos field in struct cached_dirents from int to loff_t
to support large directory offsets. This avoids overflow and
matches kernel conventions for directory positions.
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Currently, cached directory contents were not reused across subsequent
'ls' operations because the cache validity check relied on comparing
the ctx pointer, which changes with each readdir invocation. As a
result, the cached dir entries was not marked as valid and the cache was
not utilized for subsequent 'ls' operations.
This change uses the file pointer, which remains consistent across all
readdir calls for a given directory instance, to associate and validate
the cache. As a result, cached directory contents can now be
correctly reused, improving performance for repeated directory listings.
Performance gains with local windows SMB server:
Without the patch and default actimeo=1:
1000 directory enumeration operations on dir with 10k files took 135.0s
With this patch and actimeo=0:
1000 directory enumeration operations on dir with 10k files took just 5.1s
Signed-off-by: Bharath SM <bharathsm@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
The unmount process (cifs_kill_sb() calling close_all_cached_dirs()) can
race with various cached directory operations, which ultimately results
in dentries not being dropped and these kernel BUGs:
BUG: Dentry ffff88814f37e358{i=1000000000080,n=/} still in use (2) [unmount of cifs cifs]
VFS: Busy inodes after unmount of cifs (cifs)
------------[ cut here ]------------
kernel BUG at fs/super.c:661!
This happens when a cfid is in the process of being cleaned up when, and
has been removed from the cfids->entries list, including:
- Receiving a lease break from the server
- Server reconnection triggers invalidate_all_cached_dirs(), which
removes all the cfids from the list
- The laundromat thread decides to expire an old cfid.
To solve these problems, dropping the dentry is done in queued work done
in a newly-added cfid_put_wq workqueue, and close_all_cached_dirs()
flushes that workqueue after it drops all the dentries of which it's
aware. This is a global workqueue (rather than scoped to a mount), but
the queued work is minimal.
The final cleanup work for cleaning up a cfid is performed via work
queued in the serverclose_wq workqueue; this is done separate from
dropping the dentries so that close_all_cached_dirs() doesn't block on
any server operations.
Both of these queued works expect to invoked with a cfid reference and
a tcon reference to avoid those objects from being freed while the work
is ongoing.
While we're here, add proper locking to close_all_cached_dirs(), and
locking around the freeing of cfid->dentry.
Fixes: ebe98f1447 ("cifs: enable caching of directories for which a lease is held")
Cc: stable@vger.kernel.org
Signed-off-by: Paul Aurich <paul@darkrain42.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
By having laundromat kthread processing cached directories on every
second turned out to be overkill, especially when having multiple SMB
mounts.
Relax it by using a delayed worker instead that gets scheduled on
every @dir_cache_timeout (default=30) seconds per tcon.
This also fixes the 1s delay when tearing down tcon.
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Allow adjusting the maximum number of cached directories per share
(defaults to 16) via mount parm "max_cached_dirs"
Signed-off-by: Steve French <stfrench@microsoft.com>
Move CIFS/SMB3 related client and server files (cifs.ko and ksmbd.ko
and helper modules) to new fs/smb subdirectory:
fs/cifs --> fs/smb/client
fs/ksmbd --> fs/smb/server
fs/smbfs_common --> fs/smb/common
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
