fscache: Maintain a catalogue of allocated cookies

Maintain a catalogue of allocated cookies so that cookie collisions can be
handled properly.  For the moment, this just involves printing a warning
and returning a NULL cookie to the caller of fscache_acquire_cookie(), but
in future it might make sense to wait for the old cookie to finish being
cleaned up.

This requires the cookie key to be stored attached to the cookie so that we
still have the key available if the netfs relinquishes the cookie.  This is
done by an earlier patch.

The catalogue also renders redundant fscache_netfs_list (used for checking
for duplicates), so that can be removed.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index eb38f39cf832..84b90a79d75a 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -22,6 +22,7 @@
 #include <linux/list.h>
 #include <linux/pagemap.h>
 #include <linux/pagevec.h>
+#include <linux/list_bl.h>
 
 #if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
 #define fscache_available() (1)
@@ -124,7 +125,6 @@ struct fscache_netfs {
         uint32_t                        version;        /* indexing version */
         const char                      *name;          /* filesystem name */
         struct fscache_cookie           *primary_index;
-        struct list_head                link;           /* internal link */
 };
 
 /*
@@ -143,6 +143,7 @@ struct fscache_cookie {
         struct hlist_head               backing_objects; /* object(s) backing this file/index */
         const struct fscache_cookie_def *def;           /* definition */
         struct fscache_cookie           *parent;        /* parent of this entry */
+        struct hlist_bl_node            hash_link;      /* Link in hash table */
         void                            *netfs_data;    /* back pointer to netfs */
         struct radix_tree_root          stores;         /* pages to be stored on this cookie */
 #define FSCACHE_COOKIE_PENDING_TAG      0               /* pages tag: pending write to cache */
@@ -156,11 +157,14 @@ struct fscache_cookie {
 #define FSCACHE_COOKIE_RELINQUISHED     4       /* T if cookie has been relinquished */
 #define FSCACHE_COOKIE_ENABLED          5       /* T if cookie is enabled */
 #define FSCACHE_COOKIE_ENABLEMENT_LOCK  6       /* T if cookie is being en/disabled */
-#define FSCACHE_COOKIE_AUX_UPDATED      7       /* T if the auxiliary data was updated */
+#define FSCACHE_COOKIE_AUX_UPDATED      8       /* T if the auxiliary data was updated */
+#define FSCACHE_COOKIE_ACQUIRED         9       /* T if cookie is in use */
+#define FSCACHE_COOKIE_RELINQUISHING    10      /* T if cookie is being relinquished */
 
         u8                              type;           /* Type of object */
         u8                              key_len;        /* Length of index key */
         u8                              aux_len;        /* Length of auxiliary data */
+        u32                             key_hash;       /* Hash of parent, type, key, len */
         union {
                 void                    *key;           /* Index key */
                 u8                      inline_key[16]; /* - If the key is short enough */