This patchset is a first stab at adding persistent, local caching facility for
CIFS using the FS-Cache interface.
The index hierarchy which is mainly used to locate a file object or discard
a certain subset of the files cached, currently has three levels:
- Server
- Share
- File
The server index object is keyed by hostname of the server. The superblock
index object is keyed by the sharename and the inode object is keyed by the
UniqueId. The cache coherency is ensured by checking the 'LastWriteTime' and
size of file.
To use this, apply this patchset in order, mount the share with rsize=4096 and
try copying a huge file (say few hundred MBs) from mount point to local
filesystem. During the first time, the cache will be initialized. When you copy
the second time, it should read from the local cache.
To reduce the impact of page cache and see the local caching in action
readily, try doing a sync and drop the caches by doing:
sync; echo 3 > /proc/sys/vm/drop_caches
Known issues
-------------
- the cache coherency check may not be reliable always as some
CIFS servers are known not to update mtime until the filehandle is
closed.
- not all the Servers under all circumstances provide a unique
'UniqueId'.
Todo's
-------
- improvements to avoid potential key collisions
- address the above known issues
This set is lightly tested and all the bugs seen during my testing have been
fixed. However, this can be considered as an RFC for now.
Any Comments or Suggestions are welcome.
Suresh Jayaraman (10)
cifs: add kernel config option for CIFS Client caching support
cifs: guard cifsglob.h against multiple inclusion
cifs: register CIFS for caching
cifs: define server-level cache index objects and register them with FS-Cache
cifs: define superblock-level cache index objects and register them
cifs: define inode-level cache object and register them
cifs: FS-Cache page management
cifs: store pages into local cache
cifs: read pages from FS-Cache
cifs: add mount option to enable local caching
Kconfig | 9 ++
Makefile | 2
cache.c | 251 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
cifs_fs_sb.h | 1
cifsfs.c | 15 +++
cifsglob.h | 14 +++
connect.c | 16 +++
file.c | 51 +++++++++++
fscache.c | 244 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
fscache.h | 135 +++++++++++++++++++++++++++++++
inode.c | 4
11 files changed, 742 insertions(+)