cifs: read pages from FS-Cache

Read pages from a FS-Cache data storage object into a CIFS inode.

Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

3 files changed, 129 insertions, 1 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index ff726c86b290..fa04a00d126d 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1977,6 +1977,15 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
         cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
         pTcon = cifs_sb->tcon;
 
+        /*
+         * Reads as many pages as possible from fscache. Returns -ENOBUFS
+         * immediately if the cookie is negative
+         */
+        rc = cifs_readpages_from_fscache(mapping->host, mapping, page_list,
+                                         &num_pages);
+        if (rc == 0)
+                goto read_complete;
+
         cFYI(DBG2, "rpages: num pages %d", num_pages);
         for (i = 0; i < num_pages; ) {
                 unsigned contig_pages;
@@ -2087,6 +2096,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 smb_read_data = NULL;
         }
 
+read_complete:
         FreeXid(xid);
         return rc;
 }
@@ -2097,6 +2107,11 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
         char *read_data;
         int rc;
 
+        /* Is the page cached? */
+        rc = cifs_readpage_from_fscache(file->f_path.dentry->d_inode, page);
+        if (rc == 0)
+                goto read_complete;
+
         page_cache_get(page);
         read_data = kmap(page);
         /* for reads over a certain size could initiate async read ahead */
@@ -2125,6 +2140,8 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
 io_error:
         kunmap(page);
         page_cache_release(page);
+
+read_complete:
         return rc;
 }
 
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index 3b1636704c85..9f3f5c4be161 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -140,6 +140,79 @@ int cifs_fscache_release_page(struct page *page, gfp_t gfp)
         return 1;
 }
 
+static void cifs_readpage_from_fscache_complete(struct page *page, void *ctx,
+                                                int error)
+{
+        cFYI(1, "CFS: readpage_from_fscache_complete (0x%p/%d)",
+                        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;
+
+        cFYI(1, "CIFS: readpage_from_fscache(fsc:%p, p:%p, i:0x%p",
+                        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 */
+                cFYI(1, "CIFS: readpage_from_fscache: submitted");
+                return ret;
+        case -ENOBUFS:  /* page won't be cached */
+        case -ENODATA:  /* page not in cache */
+                cFYI(1, "CIFS: readpage_from_fscache %d", ret);
+                return 1;
+
+        default:
+                cERROR(1, "unknown error ret = %d", ret);
+        }
+        return ret;
+}
+
+/*
+ * Retrieve a set of pages from FS-Cache
+ */
+int __cifs_readpages_from_fscache(struct inode *inode,
+                                struct address_space *mapping,
+                                struct list_head *pages,
+                                unsigned *nr_pages)
+{
+        int ret;
+
+        cFYI(1, "CIFS: __cifs_readpages_from_fscache (0x%p/%u/0x%p)",
+                        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 */
+                cFYI(1, "CIFS: readpages_from_fscache: submitted");
+                return ret;
+
+        case -ENOBUFS:  /* some pages are not cached and can't be */
+        case -ENODATA:  /* some pages are not cached */
+                cFYI(1, "CIFS: readpages_from_fscache: no page");
+                return 1;
+
+        default:
+                cFYI(1, "unknown error ret = %d", ret);
+        }
+
+        return ret;
+}
+
 void __cifs_readpage_to_fscache(struct inode *inode, struct page *page)
 {
         int ret;
diff --git a/fs/cifs/fscache.h b/fs/cifs/fscache.h
index 1a00d70bca97..79164c66797e 100644
--- a/fs/cifs/fscache.h
+++ b/fs/cifs/fscache.h
@@ -32,7 +32,6 @@ 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);
 
@@ -50,6 +49,11 @@ extern void cifs_fscache_reset_inode_cookie(struct inode *);
 
 extern void __cifs_fscache_invalidate_page(struct page *, struct inode *);
 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_readpage_to_fscache(struct inode *, struct page *);
 
@@ -60,6 +64,26 @@ static inline void cifs_fscache_invalidate_page(struct page *page,
                 __cifs_fscache_invalidate_page(page, inode);
 }
 
+static inline int cifs_readpage_from_fscache(struct inode *inode,
+                                             struct page *page)
+{
+        if (CIFS_I(inode)->fscache)
+                return __cifs_readpage_from_fscache(inode, page);
+
+        return -ENOBUFS;
+}
+
+static inline int cifs_readpages_from_fscache(struct inode *inode,
+                                              struct address_space *mapping,
+                                              struct list_head *pages,
+                                              unsigned *nr_pages)
+{
+        if (CIFS_I(inode)->fscache)
+                return __cifs_readpages_from_fscache(inode, mapping, pages,
+                                                     nr_pages);
+        return -ENOBUFS;
+}
+
 static inline void cifs_readpage_to_fscache(struct inode *inode,
                                             struct page *page)
 {
@@ -90,6 +114,20 @@ static inline void cifs_fscache_release_page(struct page *page, gfp_t gfp)
 
 static inline int cifs_fscache_invalidate_page(struct page *page,
                         struct inode *) {}
+static inline int
+cifs_readpage_from_fscache(struct inode *inode, struct page *page)
+{
+        return -ENOBUFS;
+}
+
+static inline int cifs_readpages_from_fscache(struct inode *inode,
+                                              struct address_space *mapping,
+                                              struct list_head *pages,
+                                              unsigned *nr_pages)
+{
+        return -ENOBUFS;
+}
+
 static inline void cifs_readpage_to_fscache(struct inode *inode,
                         struct page *page) {}