Date: Fri, 03 Nov 2006 15:37:22 -0500
From: Steve Dickson <SteveD@redhat.com>
Subject: [RHEL5/FC6] [Patch 1/2] FS-Cache: error from cache: -105

The following patch series has patches to both NFS and
FS-Cache the fix bz:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=212831

NFS was filling the cache with fscache cookies that were never
going to be used. fscache cookies were being created each time a
new file handle was created, which makes sense if every fh/file
was going to be opened. Unfortunately with readdirs this is not
the case. So when an ls -R was done on a sizable tree structure,
the entire fscache is be filled up with fscache cookies that were
never going be used (i.e. because they were never going to
be opened).

So this patch disassociates the fsc cookie from the
FH and associates it a file inode and *only* file inodes.
Meaning NFS will only create cookies for files that are
opened for reading only. All other inode types are explicitly
ignored...

Actually, this greatly simplifies the NFS/FSC interface plus it also
speeds up readdirs since there is not caching done... But in the end,
we probably should cache readdir entries since they are held in pages
and they are mostly readonly data, but thats for another release..

Both of the patches have been unit tested and are currently
being worked over by jkt_home....


steved.

--- linux-2.6.18.i686/fs/nfs/inode.c.orig	2006-10-26 11:42:35.368677000 -0400
+++ linux-2.6.18.i686/fs/nfs/inode.c	2006-11-03 08:45:23.577258000 -0500
@@ -79,7 +79,7 @@ void nfs_clear_inode(struct inode *inode
 	nfs_zap_acl_cache(inode);
 	nfs_access_zap_cache(inode);
 
-	nfs_fscache_release_fh_cookie(NFS_SERVER(inode), NFS_I(inode));
+	nfs_fscache_release_cookie(inode);
 }
 
 /**
@@ -126,7 +126,7 @@ void nfs_zap_caches(struct inode *inode)
 	nfs_zap_caches_locked(inode);
 	spin_unlock(&inode->i_lock);
 
-	nfs_fscache_zap_fh_cookie(NFS_SERVER(inode), NFS_I(inode));
+	nfs_fscache_zap_cookie(inode);
 }
 
 static void nfs_zap_acl_cache(struct inode *inode)
@@ -205,7 +205,6 @@ nfs_fhget(struct super_block *sb, struct
 	};
 	struct inode *inode = ERR_PTR(-ENOENT);
 	unsigned long hash;
-	int maycache = 1;
 
 	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
 		goto out_no_inode;
@@ -257,7 +256,6 @@ nfs_fhget(struct super_block *sb, struct
 				else
 					inode->i_op = &nfs_mountpoint_inode_operations;
 				inode->i_fop = NULL;
-				maycache = 0;
 			}
 		} else if (S_ISLNK(inode->i_mode))
 			inode->i_op = &nfs_symlink_inode_operations;
@@ -288,7 +286,7 @@ nfs_fhget(struct super_block *sb, struct
 		memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
 		nfsi->access_cache = RB_ROOT;
 
-		nfs_fscache_get_fh_cookie(sb, nfsi, maycache);
+		nfs_fscache_init_cookie(inode);
 
 		unlock_new_inode(inode);
 	} else
@@ -372,7 +370,7 @@ void nfs_setattr_update_inode(struct ino
 	if ((attr->ia_valid & ATTR_SIZE) != 0) {
 		nfs_inc_stats(inode, NFSIOS_SETATTRTRUNC);
 		inode->i_size = attr->ia_size;
-		nfs_fscache_set_size(NFS_SERVER(inode), NFS_I(inode), inode->i_size);
+		nfs_fscache_set_size(inode);
 		vmtruncate(inode, attr->ia_size);
 	}
 }
@@ -557,8 +555,9 @@ int nfs_open(struct inode *inode, struct
 	ctx->mode = filp->f_mode;
 	nfs_file_set_open_context(filp, ctx);
 	put_nfs_open_context(ctx);
-	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
-		nfs_fscache_disable_fh_cookie(inode);
+
+	nfs_fscache_set_cookie(inode, filp);
+
 	return 0;
 }
 
@@ -697,7 +696,7 @@ int nfs_revalidate_mapping(struct inode 
 		}
 		spin_unlock(&inode->i_lock);
 
-		nfs_fscache_renew_fh_cookie(NFS_SERVER(inode), nfsi);
+		nfs_fscache_renew_cookie(inode);
 
 		dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated\n",
 				inode->i_sb->s_id,
@@ -932,13 +931,13 @@ static int nfs_update_inode(struct inode
 			if (data_stable) {
 				inode->i_size = new_isize;
 				invalid |= NFS_INO_INVALID_DATA;
-				nfs_fscache_set_size(NFS_SERVER(inode), nfsi, inode->i_size);
+				nfs_fscache_set_size(inode);
 			}
 			invalid |= NFS_INO_INVALID_ATTR;
 		} else if (new_isize > cur_isize) {
 			inode->i_size = new_isize;
 			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
-			nfs_fscache_set_size(NFS_SERVER(inode), nfsi, inode->i_size);
+			nfs_fscache_set_size(inode);
 		}
 		nfsi->cache_change_attribute = jiffies;
 		dprintk("NFS: isize change on server for file %s/%ld\n",
--- linux-2.6.18.i686/fs/nfs/fscache.h.orig	2006-10-26 11:42:34.920677000 -0400
+++ linux-2.6.18.i686/fs/nfs/fscache.h	2006-11-03 10:22:42.240584000 -0500
@@ -48,6 +48,13 @@ static inline void nfs_fscache_unregiste
 {
 	fscache_unregister_netfs(&nfs_cache_netfs);
 }
+/*
+ * get the per-filehandle cookie for an NFS inode
+ */
+static inline void nfs_fscache_init_cookie(struct inode *inode)
+{
+	NFS_I(inode)->fscache = NULL;
+}
 
 /*
  * get the per-client index cookie for an NFS client if the appropriate mount
@@ -90,12 +97,15 @@ static inline const char *nfs_server_fsc
 /*
  * get the per-filehandle cookie for an NFS inode
  */
-static inline void nfs_fscache_get_fh_cookie(struct super_block *sb,
-					     struct nfs_inode *nfsi,
-					     int maycache)
+static inline void nfs_fscache_enable_cookie(struct inode *inode)
 {
-	nfsi->fscache = NULL;
-	if (maycache && (NFS_SB(sb)->flags & NFS_MOUNT_FSCACHE)) {
+	struct super_block *sb = inode->i_sb;
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	if (nfsi->fscache != NULL)
+		return;
+
+	if ((NFS_SB(sb)->flags & NFS_MOUNT_FSCACHE)) {
 		nfsi->fscache = fscache_acquire_cookie(
 			NFS_SB(sb)->nfs_client->fscache,
 			&nfs_cache_fh_index_def,
@@ -111,20 +121,19 @@ static inline void nfs_fscache_get_fh_co
 /*
  * change the filesize associated with a per-filehandle cookie
  */
-static inline void nfs_fscache_set_size(struct nfs_server *server,
-					struct nfs_inode *nfsi,
-					loff_t i_size)
+static inline void nfs_fscache_set_size(struct inode *inode)
 {
-	fscache_set_i_size(nfsi->fscache, i_size);
+	fscache_set_i_size(NFS_I(inode)->fscache, inode->i_size);
 }
 
 /*
  * replace a per-filehandle cookie due to revalidation detecting a file having
  * changed on the server
  */
-static inline void nfs_fscache_renew_fh_cookie(struct nfs_server *server,
-					       struct nfs_inode *nfsi)
+static inline void nfs_fscache_renew_cookie(struct inode *inode)
 {
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_server *server = NFS_SERVER(inode);
 	struct fscache_cookie *old = nfsi->fscache;
 
 	if (nfsi->fscache) {
@@ -146,9 +155,10 @@ static inline void nfs_fscache_renew_fh_
 /*
  * release a per-filehandle cookie
  */
-static inline void nfs_fscache_release_fh_cookie(struct nfs_server *server,
-						 struct nfs_inode *nfsi)
+static inline void nfs_fscache_release_cookie(struct inode *inode)
 {
+	struct nfs_inode *nfsi = NFS_I(inode);
+
 	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
 		 nfsi, nfsi->fscache);
 
@@ -159,9 +169,10 @@ static inline void nfs_fscache_release_f
 /*
  * retire a per-filehandle cookie, destroying the data attached to it
  */
-static inline void nfs_fscache_zap_fh_cookie(struct nfs_server *server,
-					     struct nfs_inode *nfsi)
+static inline void nfs_fscache_zap_cookie(struct inode *inode)
 {
+	struct nfs_inode *nfsi = NFS_I(inode);
+
 	dfprintk(FSCACHE,"NFS: zapping cookie (0x%p/0x%p)\n",
 		nfsi, nfsi->fscache);
 
@@ -174,7 +185,7 @@ static inline void nfs_fscache_zap_fh_co
  * invalidating all the pages in the page cache relating to the associated
  * inode to clear the per-page caching
  */
-static inline void nfs_fscache_disable_fh_cookie(struct inode *inode)
+static inline void nfs_fscache_disable_cookie(struct inode *inode)
 {
 	if (NFS_I(inode)->fscache) {
 		dfprintk(FSCACHE,
@@ -186,11 +197,28 @@ static inline void nfs_fscache_disable_f
 		if (inode->i_mapping && inode->i_mapping->nrpages)
 			invalidate_inode_pages2(inode->i_mapping);
 
-		nfs_fscache_zap_fh_cookie(NFS_SERVER(inode), NFS_I(inode));
+		nfs_fscache_zap_cookie(inode);
 	}
 }
 
 /*
+ * Decide if we should enable or disable the FS cache for
+ * this inode. For now, only files that are open for read
+ * will be able to use the FS cache.
+ */
+static inline void nfs_fscache_set_cookie(struct inode *inode, 
+	struct file *filp)
+{
+	if (!S_ISREG(inode->i_mode))
+		return;
+
+	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
+		nfs_fscache_disable_cookie(inode);
+	else
+		nfs_fscache_enable_cookie(inode);
+}
+
+/*
  * install the VM ops for mmap() of an NFS file so that we can hold up writes
  * to pages on shared writable mappings until the store to the cache is
  * complete
@@ -413,28 +441,17 @@ static inline void nfs_writepage_to_fsca
 #else /* CONFIG_NFS_FSCACHE */
 static inline int nfs_fscache_register(void) { return 0; }
 static inline void nfs_fscache_unregister(void) {}
+static inline void nfs_fscache_init_cookie(struct inode *inode) {}
 static inline void nfs_fscache_get_client_cookie(struct nfs_client *clp) {}
 static inline void nfs4_fscache_get_client_cookie(struct nfs_client *clp) {}
 static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
 static inline const char *nfs_server_fscache_state(struct nfs_server *server) { return "no "; }
-
-static inline void nfs_fscache_get_fh_cookie(struct super_block *sb,
-					     struct nfs_inode *nfsi,
-					     int maycache)
-{
-}
-static inline void nfs_fscache_set_size(struct nfs_server *server,
-					struct nfs_inode *nfsi,
-					loff_t i_size)
-{
-}
-static inline void nfs_fscache_release_fh_cookie(struct nfs_server *server,
-						 struct nfs_inode *nfsi)
-{
-}
-static inline void nfs_fscache_zap_fh_cookie(struct nfs_server *server, struct nfs_inode *nfsi) {}
-static inline void nfs_fscache_renew_fh_cookie(struct nfs_server *server, struct nfs_inode *nfsi) {}
-static inline void nfs_fscache_disable_fh_cookie(struct inode *inode) {}
+static inline void nfs_fscache_enable_cookie(struct inode *inode) { }
+static inline void nfs_fscache_set_size(struct inode *inode) { }
+static inline void nfs_fscache_release_cookie(struct inode *inode) {}
+static inline void nfs_fscache_zap_cookie(struct inode *inode) {}
+static inline void nfs_fscache_renew_cookie(struct inode *inode) {}
+static inline void nfs_fscache_disable_cookie(struct inode *inode) {}
 static inline void nfs_fscache_install_vm_ops(struct inode *inode, struct vm_area_struct *vma) {}
 static inline void nfs_fscache_release_page(struct page *page) {}
 static inline void nfs_fscache_invalidate_page(struct page *page,

Date: Fri, 03 Nov 2006 15:37:34 -0500
From: Steve Dickson <SteveD@redhat.com>
Subject: [RHEL5/FC6] [Patch 2/2] FS-Cache: error from cache: -105

This second part of the series basically turns of the
logging of, what can be, a very common error...

steved.

--- linux-2.6.18.i686/fs/fscache/cookie.c.org	2006-10-26 11:42:34.864677000 -0400
+++ linux-2.6.18.i686/fs/fscache/cookie.c	2006-11-03 11:09:50.613743000 -0500
@@ -750,7 +750,8 @@ no_cache:
 	ret = -ENOMEDIUM;
 	goto error_cleanup;
 error:
-	printk(KERN_ERR "FS-Cache: error from cache: %d\n", ret);
+	if (ret != -ENOBUFS)
+		printk(KERN_ERR "FS-Cache: error from cache: %d\n", ret);
 error_cleanup:
 	if (cookie) {
 		up_write(&cookie->sem);