cifs: Support fscache indexing rewrite

Change the cifs filesystem to take account of the changes to fscache's
indexing rewrite and reenable caching in cifs.

The following changes have been made:

 (1) The fscache_netfs struct is no more, and there's no need to register
     the filesystem as a whole.

 (2) The session cookie is now an fscache_volume cookie, allocated with
     fscache_acquire_volume().  That takes three parameters: a string
     representing the "volume" in the index, a string naming the cache to
     use (or NULL) and a u64 that conveys coherency metadata for the
     volume.

     For cifs, I've made it render the volume name string as:

	"cifs,<ipaddress>,<sharename>"

     where the sharename has '/' characters replaced with ';'.

     This probably needs rethinking a bit as the total name could exceed
     the maximum filename component length.

     Further, the coherency data is currently just set to 0.  It needs
     something else doing with it - I wonder if it would suffice simply to
     sum the resource_id, vol_create_time and vol_serial_number or maybe
     hash them.

 (3) The fscache_cookie_def is no more and needed information is passed
     directly to fscache_acquire_cookie().  The cache no longer calls back
     into the filesystem, but rather metadata changes are indicated at
     other times.

     fscache_acquire_cookie() is passed the same keying and coherency
     information as before.

 (4) The functions to set/reset cookies are removed and
     fscache_use_cookie() and fscache_unuse_cookie() are used instead.

     fscache_use_cookie() is passed a flag to indicate if the cookie is
     opened for writing.  fscache_unuse_cookie() is passed updates for the
     metadata if we changed it (ie. if the file was opened for writing).

     These are called when the file is opened or closed.

 (5) cifs_setattr_*() are made to call fscache_resize() to change the size
     of the cache object.

 (6) The functions to read and write data are stubbed out pending a
     conversion to use netfslib.

Changes
=======
ver #8:
 - Abstract cache invalidation into a helper function.
 - Fix some checkpatch warnings[3].

ver #7:
 - Removed the accidentally added-back call to get the super cookie in
   cifs_root_iget().
 - Fixed the right call to cifs_fscache_get_super_cookie() to take account
   of the "-o fsc" mount flag.

ver #6:
 - Moved the change of gfpflags_allow_blocking() to current_is_kswapd() for
   cifs here.
 - Fixed one of the error paths in cifs_atomic_open() to jump around the
   call to use the cookie.
 - Fixed an additional successful return in the middle of cifs_open() to
   use the cookie on the way out.
 - Only get a volume cookie (and thus inode cookies) when "-o fsc" is
   supplied to mount.

ver #5:
 - Fixed a couple of bits of cookie handling[2]:
   - The cookie should be released in cifs_evict_inode(), not
     cifsFileInfo_put_final().  The cookie needs to persist beyond file
     closure so that writepages will be able to write to it.
   - fscache_use_cookie() needs to be called in cifs_atomic_open() as it is
     for cifs_open().

ver #4:
 - Fixed the use of sizeof with memset.
 - tcon->vol_create_time is __le64 so doesn't need cpu_to_le64().

ver #3:
 - Canonicalise the cifs coherency data to make the cache portable.
 - Set volume coherency data.

ver #2:
 - Use gfpflags_allow_blocking() rather than using flag directly.
 - Upgraded to -rc4 to allow for upstream changes[1].
 - fscache_acquire_volume() now returns errors.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
cc: Steve French <smfrench@gmail.com>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: linux-cifs@vger.kernel.org
cc: linux-cachefs@redhat.com
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=23b55d673d7527b093cd97b7c217c82e70cd1af0 [1]
Link: https://lore.kernel.org/r/3419813.1641592362@warthog.procyon.org.uk/ [2]
Link: https://lore.kernel.org/r/CAH2r5muTanw9pJqzAHd01d9A8keeChkzGsCEH6=0rHutVLAF-A@mail.gmail.com/ [3]
Link: https://lore.kernel.org/r/163819671009.215744.11230627184193298714.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906982979.143852.10672081929614953210.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967187187.1823006.247415138444991444.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021579335.640689.2681324337038770579.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/3462849.1641593783@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/1318953.1642024578@warthog.procyon.org.uk/ # v6
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 45 insertions, 83 deletions

diff --git a/fs/cifs/fscache.h b/fs/cifs/fscache.h
index 9baa1d0f22bd..c6ca49ac33d4 100644
--- a/fs/cifs/fscache.h
+++ b/fs/cifs/fscache.h
@@ -13,84 +13,71 @@
 
 #include "cifsglob.h"
 
-#ifdef CONFIG_CIFS_FSCACHE
-
 /*
- * Auxiliary data attached to CIFS superblock within the cache
+ * Coherency data attached to CIFS volume within the cache
  */
-struct cifs_fscache_super_auxdata {
-	u64	resource_id;		/* unique server resource id */
+struct cifs_fscache_volume_coherency_data {
+	__le64	resource_id;		/* unique server resource id */
 	__le64	vol_create_time;
-	u32	vol_serial_number;
+	__le32	vol_serial_number;
 } __packed;
 
 /*
- * Auxiliary data attached to CIFS inode within the cache
+ * Coherency data attached to CIFS inode within the cache.
  */
-struct cifs_fscache_inode_auxdata {
-	u64 last_write_time_sec;
-	u64 last_change_time_sec;
-	u32 last_write_time_nsec;
-	u32 last_change_time_nsec;
-	u64 eof;
+struct cifs_fscache_inode_coherency_data {
+	__le64 last_write_time_sec;
+	__le64 last_change_time_sec;
+	__le32 last_write_time_nsec;
+	__le32 last_change_time_nsec;
 };
 
-/*
- * cache.c
- */
-extern struct fscache_netfs cifs_fscache_netfs;
-extern const struct fscache_cookie_def cifs_fscache_server_index_def;
-extern const struct fscache_cookie_def cifs_fscache_super_index_def;
-extern const struct fscache_cookie_def cifs_fscache_inode_object_def;
-
-extern int cifs_fscache_register(void);
-extern void cifs_fscache_unregister(void);
+#ifdef CONFIG_CIFS_FSCACHE
 
 /*
  * fscache.c
  */
-extern void cifs_fscache_get_client_cookie(struct TCP_Server_Info *);
-extern void cifs_fscache_release_client_cookie(struct TCP_Server_Info *);
-extern void cifs_fscache_get_super_cookie(struct cifs_tcon *);
+extern int cifs_fscache_get_super_cookie(struct cifs_tcon *);
 extern void cifs_fscache_release_super_cookie(struct cifs_tcon *);
 
+extern void cifs_fscache_get_inode_cookie(struct inode *inode);
 extern void cifs_fscache_release_inode_cookie(struct inode *);
-extern void cifs_fscache_update_inode_cookie(struct inode *inode);
-extern void cifs_fscache_set_inode_cookie(struct inode *, struct file *);
-extern void cifs_fscache_reset_inode_cookie(struct inode *);
+extern void cifs_fscache_unuse_inode_cookie(struct inode *inode, bool update);
+
+static inline
+void cifs_fscache_fill_coherency(struct inode *inode,
+				 struct cifs_fscache_inode_coherency_data *cd)
+{
+	struct cifsInodeInfo *cifsi = CIFS_I(inode);
+
+	memset(cd, 0, sizeof(*cd));
+	cd->last_write_time_sec   = cpu_to_le64(cifsi->vfs_inode.i_mtime.tv_sec);
+	cd->last_write_time_nsec  = cpu_to_le32(cifsi->vfs_inode.i_mtime.tv_nsec);
+	cd->last_change_time_sec  = cpu_to_le64(cifsi->vfs_inode.i_ctime.tv_sec);
+	cd->last_change_time_nsec = cpu_to_le32(cifsi->vfs_inode.i_ctime.tv_nsec);
+}
+
 
-extern void __cifs_fscache_invalidate_page(struct page *, struct inode *);
-extern void __cifs_fscache_wait_on_page_write(struct inode *inode, struct page *page);
-extern void __cifs_fscache_uncache_page(struct inode *inode, struct page *page);
 extern int cifs_fscache_release_page(struct page *page, gfp_t gfp);
 extern int __cifs_readpage_from_fscache(struct inode *, struct page *);
 extern int __cifs_readpages_from_fscache(struct inode *,
 					 struct address_space *,
 					 struct list_head *,
 					 unsigned *);
-extern void __cifs_fscache_readpages_cancel(struct inode *, struct list_head *);
-
 extern void __cifs_readpage_to_fscache(struct inode *, struct page *);
 
-static inline void cifs_fscache_invalidate_page(struct page *page,
-					       struct inode *inode)
+static inline struct fscache_cookie *cifs_inode_cookie(struct inode *inode)
 {
-	if (PageFsCache(page))
-		__cifs_fscache_invalidate_page(page, inode);
+	return CIFS_I(inode)->fscache;
 }
 
-static inline void cifs_fscache_wait_on_page_write(struct inode *inode,
-						   struct page *page)
+static inline void cifs_invalidate_cache(struct inode *inode, unsigned int flags)
 {
-	if (PageFsCache(page))
-		__cifs_fscache_wait_on_page_write(inode, page);
-}
+	struct cifs_fscache_inode_coherency_data cd;
 
-static inline void cifs_fscache_uncache_page(struct inode *inode,
-						   struct page *page)
-{
-	if (PageFsCache(page))
-		__cifs_fscache_uncache_page(inode, page);
+	cifs_fscache_fill_coherency(inode, &cd);
+	fscache_invalidate(cifs_inode_cookie(inode), &cd,
+			   i_size_read(inode), flags);
 }
 
 static inline int cifs_readpage_from_fscache(struct inode *inode,
@@ -120,41 +107,21 @@ static inline void cifs_readpage_to_fscache(struct inode *inode,
 		__cifs_readpage_to_fscache(inode, page);
 }
 
-static inline void cifs_fscache_readpages_cancel(struct inode *inode,
-						 struct list_head *pages)
+#else /* CONFIG_CIFS_FSCACHE */
+static inline
+void cifs_fscache_fill_coherency(struct inode *inode,
+				 struct cifs_fscache_inode_coherency_data *cd)
 {
-	if (CIFS_I(inode)->fscache)
-		return __cifs_fscache_readpages_cancel(inode, pages);
 }
 
-#else /* CONFIG_CIFS_FSCACHE */
-static inline int cifs_fscache_register(void) { return 0; }
-static inline void cifs_fscache_unregister(void) {}
-
-static inline void
-cifs_fscache_get_client_cookie(struct TCP_Server_Info *server) {}
-static inline void
-cifs_fscache_release_client_cookie(struct TCP_Server_Info *server) {}
-static inline void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon) {}
-static inline void
-cifs_fscache_release_super_cookie(struct cifs_tcon *tcon) {}
+static inline int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon) { return 0; }
+static inline void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon) {}
 
+static inline void cifs_fscache_get_inode_cookie(struct inode *inode) {}
 static inline void cifs_fscache_release_inode_cookie(struct inode *inode) {}
-static inline void cifs_fscache_update_inode_cookie(struct inode *inode) {}
-static inline void cifs_fscache_set_inode_cookie(struct inode *inode,
-						 struct file *filp) {}
-static inline void cifs_fscache_reset_inode_cookie(struct inode *inode) {}
-static inline int cifs_fscache_release_page(struct page *page, gfp_t gfp)
-{
-	return 1; /* May release page */
-}
-
-static inline void cifs_fscache_invalidate_page(struct page *page,
-			struct inode *inode) {}
-static inline void cifs_fscache_wait_on_page_write(struct inode *inode,
-						   struct page *page) {}
-static inline void cifs_fscache_uncache_page(struct inode *inode,
-						   struct page *page) {}
+static inline void cifs_fscache_unuse_inode_cookie(struct inode *inode, bool update) {}
+static inline struct fscache_cookie *cifs_inode_cookie(struct inode *inode) { return NULL; }
+static inline void cifs_invalidate_cache(struct inode *inode, unsigned int flags) {}
 
 static inline int
 cifs_readpage_from_fscache(struct inode *inode, struct page *page)
@@ -173,11 +140,6 @@ static inline int cifs_readpages_from_fscache(struct inode *inode,
 static inline void cifs_readpage_to_fscache(struct inode *inode,
 			struct page *page) {}
 
-static inline void cifs_fscache_readpages_cancel(struct inode *inode,
-						 struct list_head *pages)
-{
-}
-
 #endif /* CONFIG_CIFS_FSCACHE */
 
 #endif /* _CIFS_FSCACHE_H */