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authorJeff Layton <jlayton@redhat.com>2012-12-03 06:05:29 -0500
committerSteve French <smfrench@gmail.com>2012-12-08 22:04:25 -0600
commitfaa65f07d21e7d37190c91fdcf9f940d733ae3cc (patch)
tree68f77248b24fa59c3ec6218c6accfe0404f10f32 /fs/cifs/cifsproto.h
parent03eca704cfa426aebf6edcc0208536835c109a9f (diff)
cifs: simplify id_to_sid and sid_to_id mapping code
The cifs.idmap handling code currently causes the kernel to cache the data from userspace twice. It first looks in a rbtree to see if there is a matching entry for the given id. If there isn't then it calls request_key which then checks its cache and then calls out to userland if it doesn't have one. If the userland program establishes a mapping and downcalls with that info, it then gets cached in the keyring and in this rbtree. Aside from the double memory usage and the performance penalty in doing all of these extra copies, there are some nasty bugs in here too. The code declares four rbtrees and spinlocks to protect them, but only seems to use two of them. The upshot is that the same tree is used to hold (eg) uid:sid and sid:uid mappings. The comparitors aren't equipped to deal with that. I think we'd be best off to remove a layer of caching in this code. If this was originally done for performance reasons, then that really seems like a premature optimization. This patch does that -- it removes the rbtrees and the locks that protect them and simply has the code do a request_key call on each call into sid_to_id and id_to_sid. This greatly simplifies this code and should roughly halve the memory utilization from using the idmapping code. Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
Diffstat (limited to 'fs/cifs/cifsproto.h')
-rw-r--r--fs/cifs/cifsproto.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index a152f3645b09..1988c1baa224 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -58,7 +58,6 @@ do { \
} while (0)
extern int init_cifs_idmap(void);
extern void exit_cifs_idmap(void);
-extern void cifs_destroy_idmaptrees(void);
extern char *build_path_from_dentry(struct dentry *);
extern char *cifs_build_path_to_root(struct smb_vol *vol,
struct cifs_sb_info *cifs_sb,