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, 80 insertions, 253 deletions

diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index 003c5f1f4dfb..efaac4d5ff55 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -12,250 +12,136 @@
 #include "cifs_fs_sb.h"
 #include "cifsproto.h"
 
-/*
- * Key layout of CIFS server cache index object
- */
-struct cifs_server_key {
-	__u64 conn_id;
-} __packed;
-
-/*
- * Get a cookie for a server object keyed by {IPaddress,port,family} tuple
- */
-void cifs_fscache_get_client_cookie(struct TCP_Server_Info *server)
-{
-	struct cifs_server_key key;
-
-	/*
-	 * Check if cookie was already initialized so don't reinitialize it.
-	 * In the future, as we integrate with newer fscache features,
-	 * we may want to instead add a check if cookie has changed
-	 */
-	if (server->fscache)
-		return;
-
-	memset(&key, 0, sizeof(key));
-	key.conn_id = server->conn_id;
-
-	server->fscache =
-		fscache_acquire_cookie(cifs_fscache_netfs.primary_index,
-				       &cifs_fscache_server_index_def,
-				       &key, sizeof(key),
-				       NULL, 0,
-				       server, 0, true);
-	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
-		 __func__, server, server->fscache);
-}
-
-void cifs_fscache_release_client_cookie(struct TCP_Server_Info *server)
+static void cifs_fscache_fill_volume_coherency(
+	struct cifs_tcon *tcon,
+	struct cifs_fscache_volume_coherency_data *cd)
 {
-	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
-		 __func__, server, server->fscache);
-	fscache_relinquish_cookie(server->fscache, NULL, false);
-	server->fscache = NULL;
+	memset(cd, 0, sizeof(*cd));
+	cd->resource_id		= cpu_to_le64(tcon->resource_id);
+	cd->vol_create_time	= tcon->vol_create_time;
+	cd->vol_serial_number	= cpu_to_le32(tcon->vol_serial_number);
 }
 
-void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
+int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 {
+	struct cifs_fscache_volume_coherency_data cd;
 	struct TCP_Server_Info *server = tcon->ses->server;
+	struct fscache_volume *vcookie;
+	const struct sockaddr *sa = (struct sockaddr *)&server->dstaddr;
+	size_t slen, i;
 	char *sharename;
-	struct cifs_fscache_super_auxdata auxdata;
+	char *key;
+	int ret = -ENOMEM;
 
-	/*
-	 * Check if cookie was already initialized so don't reinitialize it.
-	 * In the future, as we integrate with newer fscache features,
-	 * we may want to instead add a check if cookie has changed
-	 */
-	if (tcon->fscache)
-		return;
+	tcon->fscache = NULL;
+	switch (sa->sa_family) {
+	case AF_INET:
+	case AF_INET6:
+		break;
+	default:
+		cifs_dbg(VFS, "Unknown network family '%d'\n", sa->sa_family);
+		return -EINVAL;
+	}
+
+	memset(&key, 0, sizeof(key));
 
 	sharename = extract_sharename(tcon->treeName);
 	if (IS_ERR(sharename)) {
 		cifs_dbg(FYI, "%s: couldn't extract sharename\n", __func__);
-		tcon->fscache = NULL;
-		return;
+		return -EINVAL;
 	}
 
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.resource_id = tcon->resource_id;
-	auxdata.vol_create_time = tcon->vol_create_time;
-	auxdata.vol_serial_number = tcon->vol_serial_number;
+	slen = strlen(sharename);
+	for (i = 0; i < slen; i++)
+		if (sharename[i] == '/')
+			sharename[i] = ';';
+
+	key = kasprintf(GFP_KERNEL, "cifs,%pISpc,%s", sa, sharename);
+	if (!key)
+		goto out;
+
+	cifs_fscache_fill_volume_coherency(tcon, &cd);
+	vcookie = fscache_acquire_volume(key,
+					 NULL, /* preferred_cache */
+					 &cd, sizeof(cd));
+	cifs_dbg(FYI, "%s: (%s/0x%p)\n", __func__, key, vcookie);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			ret = PTR_ERR(vcookie);
+			goto out_2;
+		}
+		pr_err("Cache volume key already in use (%s)\n", key);
+		vcookie = NULL;
+	}
 
-	tcon->fscache =
-		fscache_acquire_cookie(server->fscache,
-				       &cifs_fscache_super_index_def,
-				       sharename, strlen(sharename),
-				       &auxdata, sizeof(auxdata),
-				       tcon, 0, true);
+	tcon->fscache = vcookie;
+	ret = 0;
+out_2:
+	kfree(key);
+out:
 	kfree(sharename);
-	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
-		 __func__, server->fscache, tcon->fscache);
+	return ret;
 }
 
 void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
 {
-	struct cifs_fscache_super_auxdata auxdata;
-
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.resource_id = tcon->resource_id;
-	auxdata.vol_create_time = tcon->vol_create_time;
-	auxdata.vol_serial_number = tcon->vol_serial_number;
+	struct cifs_fscache_volume_coherency_data cd;
 
 	cifs_dbg(FYI, "%s: (0x%p)\n", __func__, tcon->fscache);
-	fscache_relinquish_cookie(tcon->fscache, &auxdata, false);
-	tcon->fscache = NULL;
-}
-
-static void cifs_fscache_acquire_inode_cookie(struct cifsInodeInfo *cifsi,
-					      struct cifs_tcon *tcon)
-{
-	struct cifs_fscache_inode_auxdata auxdata;
 
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.eof = cifsi->server_eof;
-	auxdata.last_write_time_sec = cifsi->vfs_inode.i_mtime.tv_sec;
-	auxdata.last_change_time_sec = cifsi->vfs_inode.i_ctime.tv_sec;
-	auxdata.last_write_time_nsec = cifsi->vfs_inode.i_mtime.tv_nsec;
-	auxdata.last_change_time_nsec = cifsi->vfs_inode.i_ctime.tv_nsec;
-
-	cifsi->fscache =
-		fscache_acquire_cookie(tcon->fscache,
-				       &cifs_fscache_inode_object_def,
-				       &cifsi->uniqueid, sizeof(cifsi->uniqueid),
-				       &auxdata, sizeof(auxdata),
-				       cifsi, cifsi->vfs_inode.i_size, true);
+	cifs_fscache_fill_volume_coherency(tcon, &cd);
+	fscache_relinquish_volume(tcon->fscache, &cd, false);
+	tcon->fscache = NULL;
 }
 
-static void cifs_fscache_enable_inode_cookie(struct inode *inode)
+void cifs_fscache_get_inode_cookie(struct inode *inode)
 {
+	struct cifs_fscache_inode_coherency_data cd;
 	struct cifsInodeInfo *cifsi = CIFS_I(inode);
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
-	if (cifsi->fscache)
-		return;
-
-	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_FSCACHE))
-		return;
-
-	cifs_fscache_acquire_inode_cookie(cifsi, tcon);
+	cifs_fscache_fill_coherency(&cifsi->vfs_inode, &cd);
 
-	cifs_dbg(FYI, "%s: got FH cookie (0x%p/0x%p)\n",
-		 __func__, tcon->fscache, cifsi->fscache);
+	cifsi->fscache =
+		fscache_acquire_cookie(tcon->fscache, 0,
+				       &cifsi->uniqueid, sizeof(cifsi->uniqueid),
+				       &cd, sizeof(cd),
+				       i_size_read(&cifsi->vfs_inode));
 }
 
-void cifs_fscache_release_inode_cookie(struct inode *inode)
+void cifs_fscache_unuse_inode_cookie(struct inode *inode, bool update)
 {
-	struct cifs_fscache_inode_auxdata auxdata;
-	struct cifsInodeInfo *cifsi = CIFS_I(inode);
-
-	if (cifsi->fscache) {
-		memset(&auxdata, 0, sizeof(auxdata));
-		auxdata.eof = cifsi->server_eof;
-		auxdata.last_write_time_sec = cifsi->vfs_inode.i_mtime.tv_sec;
-		auxdata.last_change_time_sec = cifsi->vfs_inode.i_ctime.tv_sec;
-		auxdata.last_write_time_nsec = cifsi->vfs_inode.i_mtime.tv_nsec;
-		auxdata.last_change_time_nsec = cifsi->vfs_inode.i_ctime.tv_nsec;
+	if (update) {
+		struct cifs_fscache_inode_coherency_data cd;
+		loff_t i_size = i_size_read(inode);
 
-		cifs_dbg(FYI, "%s: (0x%p)\n", __func__, cifsi->fscache);
-		/* fscache_relinquish_cookie does not seem to update auxdata */
-		fscache_update_cookie(cifsi->fscache, &auxdata);
-		fscache_relinquish_cookie(cifsi->fscache, &auxdata, false);
-		cifsi->fscache = NULL;
+		cifs_fscache_fill_coherency(inode, &cd);
+		fscache_unuse_cookie(cifs_inode_cookie(inode), &cd, &i_size);
+	} else {
+		fscache_unuse_cookie(cifs_inode_cookie(inode), NULL, NULL);
 	}
 }
 
-void cifs_fscache_update_inode_cookie(struct inode *inode)
+void cifs_fscache_release_inode_cookie(struct inode *inode)
 {
-	struct cifs_fscache_inode_auxdata auxdata;
 	struct cifsInodeInfo *cifsi = CIFS_I(inode);
 
 	if (cifsi->fscache) {
-		memset(&auxdata, 0, sizeof(auxdata));
-		auxdata.eof = cifsi->server_eof;
-		auxdata.last_write_time_sec = cifsi->vfs_inode.i_mtime.tv_sec;
-		auxdata.last_change_time_sec = cifsi->vfs_inode.i_ctime.tv_sec;
-		auxdata.last_write_time_nsec = cifsi->vfs_inode.i_mtime.tv_nsec;
-		auxdata.last_change_time_nsec = cifsi->vfs_inode.i_ctime.tv_nsec;
-
 		cifs_dbg(FYI, "%s: (0x%p)\n", __func__, cifsi->fscache);
-		fscache_update_cookie(cifsi->fscache, &auxdata);
-	}
-}
-
-void cifs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
-{
-	cifs_fscache_enable_inode_cookie(inode);
-}
-
-void cifs_fscache_reset_inode_cookie(struct inode *inode)
-{
-	struct cifsInodeInfo *cifsi = CIFS_I(inode);
-	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
-	struct fscache_cookie *old = cifsi->fscache;
-
-	if (cifsi->fscache) {
-		/* retire the current fscache cache and get a new one */
-		fscache_relinquish_cookie(cifsi->fscache, NULL, true);
-
-		cifs_fscache_acquire_inode_cookie(cifsi, tcon);
-		cifs_dbg(FYI, "%s: new cookie 0x%p oldcookie 0x%p\n",
-			 __func__, cifsi->fscache, old);
+		fscache_relinquish_cookie(cifsi->fscache, false);
+		cifsi->fscache = NULL;
 	}
 }
 
-int cifs_fscache_release_page(struct page *page, gfp_t gfp)
-{
-	if (PageFsCache(page)) {
-		struct inode *inode = page->mapping->host;
-		struct cifsInodeInfo *cifsi = CIFS_I(inode);
-
-		cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
-			 __func__, page, cifsi->fscache);
-		if (!fscache_maybe_release_page(cifsi->fscache, page, gfp))
-			return 0;
-	}
-
-	return 1;
-}
-
-static void cifs_readpage_from_fscache_complete(struct page *page, void *ctx,
-						int error)
-{
-	cifs_dbg(FYI, "%s: (0x%p/%d)\n", __func__, page, error);
-	if (!error)
-		SetPageUptodate(page);
-	unlock_page(page);
-}
-
 /*
  * Retrieve a page from FS-Cache
  */
 int __cifs_readpage_from_fscache(struct inode *inode, struct page *page)
 {
-	int ret;
-
 	cifs_dbg(FYI, "%s: (fsc:%p, p:%p, i:0x%p\n",
 		 __func__, CIFS_I(inode)->fscache, page, inode);
-	ret = fscache_read_or_alloc_page(CIFS_I(inode)->fscache, page,
-					 cifs_readpage_from_fscache_complete,
-					 NULL,
-					 GFP_KERNEL);
-	switch (ret) {
-
-	case 0: /* page found in fscache, read submitted */
-		cifs_dbg(FYI, "%s: submitted\n", __func__);
-		return ret;
-	case -ENOBUFS:	/* page won't be cached */
-	case -ENODATA:	/* page not in cache */
-		cifs_dbg(FYI, "%s: %d\n", __func__, ret);
-		return 1;
-
-	default:
-		cifs_dbg(VFS, "unknown error ret = %d\n", ret);
-	}
-	return ret;
+	return -ENOBUFS; // Needs conversion to using netfslib
 }
 
 /*
@@ -266,78 +152,19 @@ int __cifs_readpages_from_fscache(struct inode *inode,
 				struct list_head *pages,
 				unsigned *nr_pages)
 {
-	int ret;
-
 	cifs_dbg(FYI, "%s: (0x%p/%u/0x%p)\n",
 		 __func__, CIFS_I(inode)->fscache, *nr_pages, inode);
-	ret = fscache_read_or_alloc_pages(CIFS_I(inode)->fscache, mapping,
-					  pages, nr_pages,
-					  cifs_readpage_from_fscache_complete,
-					  NULL,
-					  mapping_gfp_mask(mapping));
-	switch (ret) {
-	case 0:	/* read submitted to the cache for all pages */
-		cifs_dbg(FYI, "%s: submitted\n", __func__);
-		return ret;
-
-	case -ENOBUFS:	/* some pages are not cached and can't be */
-	case -ENODATA:	/* some pages are not cached */
-		cifs_dbg(FYI, "%s: no page\n", __func__);
-		return 1;
-
-	default:
-		cifs_dbg(FYI, "unknown error ret = %d\n", ret);
-	}
-
-	return ret;
+	return -ENOBUFS; // Needs conversion to using netfslib
 }
 
 void __cifs_readpage_to_fscache(struct inode *inode, struct page *page)
 {
 	struct cifsInodeInfo *cifsi = CIFS_I(inode);
-	int ret;
 
 	WARN_ON(!cifsi->fscache);
 
 	cifs_dbg(FYI, "%s: (fsc: %p, p: %p, i: %p)\n",
 		 __func__, cifsi->fscache, page, inode);
-	ret = fscache_write_page(cifsi->fscache, page,
-				 cifsi->vfs_inode.i_size, GFP_KERNEL);
-	if (ret != 0)
-		fscache_uncache_page(cifsi->fscache, page);
-}
-
-void __cifs_fscache_readpages_cancel(struct inode *inode, struct list_head *pages)
-{
-	cifs_dbg(FYI, "%s: (fsc: %p, i: %p)\n",
-		 __func__, CIFS_I(inode)->fscache, inode);
-	fscache_readpages_cancel(CIFS_I(inode)->fscache, pages);
-}
-
-void __cifs_fscache_invalidate_page(struct page *page, struct inode *inode)
-{
-	struct cifsInodeInfo *cifsi = CIFS_I(inode);
-	struct fscache_cookie *cookie = cifsi->fscache;
-
-	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n", __func__, page, cookie);
-	fscache_wait_on_page_write(cookie, page);
-	fscache_uncache_page(cookie, page);
-}
-
-void __cifs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
-{
-	struct cifsInodeInfo *cifsi = CIFS_I(inode);
-	struct fscache_cookie *cookie = cifsi->fscache;
-
-	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n", __func__, page, cookie);
-	fscache_wait_on_page_write(cookie, page);
-}
-
-void __cifs_fscache_uncache_page(struct inode *inode, struct page *page)
-{
-	struct cifsInodeInfo *cifsi = CIFS_I(inode);
-	struct fscache_cookie *cookie = cifsi->fscache;
 
-	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n", __func__, page, cookie);
-	fscache_uncache_page(cookie, page);
+	// Needs conversion to using netfslib
 }