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From:   Eric Van Hensbergen <ericvh@kernel.org>
Date:   Sat, 01 Apr 2023 23:16:23 +0000
Subject: [PATCH] fs/9p: Rework cache modes and add new options to
 Documentation
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Message-Id: <20230401-ericvh-dev-rework-cache-options-v1-1-12d3adbdd33a@kernel.org>
To:     Latchesar Ionkov <lucho@ionkov.net>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Christian Schoenebeck <linux_oss@crudebyte.com>,
        v9fs@lists.linux.dev
Cc:     v9fs-developer@lists.sourceforge.net, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Eric Van Hensbergen <ericvh@kernel.org>
Precedence: bulk

Switch cache modes to a bit-mask and use legacy
cache names as shortcuts.  Update documentation to
include information on both shortcuts and bitmasks.

This patch also fixes missing guards related to fscache.

Update the documentation for new mount flags
and cache modes.

Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
---
 Documentation/filesystems/9p.rst | 50 ++++++++++++++++++++++--------
 fs/9p/cache.h                    |  3 +-
 fs/9p/fid.h                      |  4 +--
 fs/9p/v9fs.c                     | 34 +++++++-------------
 fs/9p/v9fs.h                     | 67 ++++++++++++++++++++++++++--------------
 fs/9p/vfs_addr.c                 | 37 +++++++++++++---------
 fs/9p/vfs_file.c                 |  6 ++--
 fs/9p/vfs_inode.c                | 28 ++++++++++++-----
 fs/9p/vfs_inode_dotl.c           | 24 +++++++-------
 fs/9p/vfs_super.c                |  4 +--
 10 files changed, 154 insertions(+), 103 deletions(-)

diff --git a/Documentation/filesystems/9p.rst b/Documentation/filesystems/9p.rst
index 0e800b8f73cc..d79bf4e41a71 100644
--- a/Documentation/filesystems/9p.rst
+++ b/Documentation/filesystems/9p.rst
@@ -78,19 +78,39 @@ Options
   		offering several exported file systems.
 
   cache=mode	specifies a caching policy.  By default, no caches are used.
-
-                        none
-				default no cache policy, metadata and data
-                                alike are synchronous.
-			loose
-				no attempts are made at consistency,
-                                intended for exclusive, read-only mounts
-                        fscache
-				use FS-Cache for a persistent, read-only
-				cache backend.
-                        mmap
-				minimal cache that is only used for read-write
-                                mmap.  Northing else is cached, like cache=none
+		The mode can be specified as a bitmask or by using one of the
+		prexisting common 'shortcuts'.
+		The bitmask is described below: (unspecified bits are reserved)
+
+			==========	================================================
+			0b00000000	all caches disabled, mmap disabled
+			0b00000001	file caches enabled
+			0b00000010	meta-data caches enabled
+			0b00000100	writeback behavior (as opposed to writethrough)
+			0b00001000	loose caches (no explicit consistency with server)
+			0b10000000	fscache enabled for persistent caching
+			=========	================================================
+
+		The current shortcuts and their associated bitmask are:
+
+			=========	=============================================
+			none		0b00000000 (no caching)
+			readahead	0b00000001 (only read-ahead file caching)
+			mmap		0b00000101 (read-ahead + writeback file cache)
+			loose		0b00001111 (non-coherent file and meta-data caches)
+			fscache		0b10001111 (persistent loose cache)
+			=========	=============================================
+
+		NOTE: only these shortcuts are tested modes of operation at the
+		moment, so using other combinations of bit-patterns is not
+		known to work.  Work on better cache support is in progress.
+
+		IMPORTANT: loose caches (and by extension at the moment fscache)
+		do not necessarily validate cached values on the server.  In other
+		words changes on the server are not guaranteed to be reflected
+		on the client system.  Only use this mode of operation if you
+		have an exclusive mount and the server will modify the filesystem
+		underneath you.
 
   debug=n	specifies debug level.  The debug level is a bitmask.
 
@@ -137,6 +157,10 @@ Options
   		This can be used to share devices/named pipes/sockets between
 		hosts.  This functionality will be expanded in later versions.
 
+  directio	bypass page cache on all read/write operations
+
+  ignoreqv	ignore qid.version==0 as a marker to ignore cache
+
   noxattr	do not offer xattr functions on this mount.
 
   access	there are four access modes.
diff --git a/fs/9p/cache.h b/fs/9p/cache.h
index 1923affcdc62..ee1b6b06a2fd 100644
--- a/fs/9p/cache.h
+++ b/fs/9p/cache.h
@@ -8,9 +8,8 @@
 #ifndef _9P_CACHE_H
 #define _9P_CACHE_H
 
-#include <linux/fscache.h>
-
 #ifdef CONFIG_9P_FSCACHE
+#include <linux/fscache.h>
 
 extern int v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses,
 					  const char *dev_name);
diff --git a/fs/9p/fid.h b/fs/9p/fid.h
index 11576e1364bf..0c51889a60b3 100644
--- a/fs/9p/fid.h
+++ b/fs/9p/fid.h
@@ -56,11 +56,9 @@ static inline void v9fs_fid_add_modes(struct p9_fid *fid, int s_flags,
 	   ((fid->qid.version == 0) && !(s_flags & V9FS_IGNORE_QV)) ||
 	   (s_flags & V9FS_DIRECT_IO) || (f_flags & O_DIRECT)) {
 		fid->mode |= P9L_DIRECT; /* no read or write cache */
-	} else if ((s_cache < CACHE_WRITEBACK) ||
+	} else if ((!(s_cache & CACHE_WRITEBACK)) ||
 				(f_flags & O_DSYNC) | (s_flags & V9FS_SYNC)) {
 		fid->mode |= P9L_NOWRITECACHE;
-	} else if (s_cache == CACHE_LOOSE) {
-		fid->mode |= P9L_LOOSE; /* noncoherent cache */
 	}
 }
 #endif
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 43d3806150a9..c7f774fe398f 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -66,40 +66,30 @@ static const match_table_t tokens = {
 	{Opt_err, NULL}
 };
 
-static const char *const v9fs_cache_modes[nr__p9_cache_modes] = {
-	[CACHE_NONE]		= "none",
-	[CACHE_READAHEAD]	= "readahead",
-	[CACHE_WRITEBACK]	= "writeback",
-	[CACHE_MMAP]		= "mmap",
-	[CACHE_LOOSE]		= "loose",
-	[CACHE_FSCACHE]		= "fscache",
-};
-
 /* Interpret mount options for cache mode */
 static int get_cache_mode(char *s)
 {
 	int version = -EINVAL;
 
 	if (!strcmp(s, "loose")) {
-		version = CACHE_LOOSE;
+		version = CACHE_SC_LOOSE;
 		p9_debug(P9_DEBUG_9P, "Cache mode: loose\n");
 	} else if (!strcmp(s, "fscache")) {
-		version = CACHE_FSCACHE;
+		version = CACHE_SC_FSCACHE;
 		p9_debug(P9_DEBUG_9P, "Cache mode: fscache\n");
 	} else if (!strcmp(s, "mmap")) {
-		version = CACHE_MMAP;
+		version = CACHE_SC_MMAP;
 		p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
-	} else if (!strcmp(s, "writeback")) {
-		version = CACHE_WRITEBACK;
-		p9_debug(P9_DEBUG_9P, "Cache mode: writeback\n");
 	} else if (!strcmp(s, "readahead")) {
-		version = CACHE_READAHEAD;
+		version = CACHE_SC_READAHEAD;
 		p9_debug(P9_DEBUG_9P, "Cache mode: readahead\n");
 	} else if (!strcmp(s, "none")) {
-		version = CACHE_NONE;
+		version = CACHE_SC_NONE;
 		p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
-	} else
-		pr_info("Unknown Cache mode %s\n", s);
+	} else if (kstrtoint(s, 0, &version) != 0) {
+		version = -EINVAL;
+		pr_info("Unknown Cache mode or invalid value %s\n", s);
+	}
 	return version;
 }
 
@@ -127,9 +117,9 @@ int v9fs_show_options(struct seq_file *m, struct dentry *root)
 	if (v9ses->nodev)
 		seq_puts(m, ",nodevmap");
 	if (v9ses->cache)
-		seq_printf(m, ",cache=%s", v9fs_cache_modes[v9ses->cache]);
+		seq_printf(m, ",cache=%x", v9ses->cache);
 #ifdef CONFIG_9P_FSCACHE
-	if (v9ses->cachetag && v9ses->cache == CACHE_FSCACHE)
+	if (v9ses->cachetag && (v9ses->cache & CACHE_FSCACHE))
 		seq_printf(m, ",cachetag=%s", v9ses->cachetag);
 #endif
 
@@ -481,7 +471,7 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 
 #ifdef CONFIG_9P_FSCACHE
 	/* register the session for caching */
-	if (v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & CACHE_FSCACHE) {
 		rc = v9fs_cache_session_get_cookie(v9ses, dev_name);
 		if (rc < 0)
 			goto err_clnt;
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 999cdbcbfed9..06a2514f0d88 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -31,35 +31,54 @@
 #define V9FS_ACL_MASK V9FS_POSIX_ACL
 
 enum p9_session_flags {
-	V9FS_PROTO_2000U	= 0x01,
-	V9FS_PROTO_2000L	= 0x02,
-	V9FS_ACCESS_SINGLE	= 0x04,
-	V9FS_ACCESS_USER	= 0x08,
-	V9FS_ACCESS_CLIENT	= 0x10,
-	V9FS_POSIX_ACL		= 0x20,
-	V9FS_NO_XATTR		= 0x40,
-	V9FS_IGNORE_QV		= 0x80, /* ignore qid.version for cache hints */
-	V9FS_DIRECT_IO		= 0x100,
-	V9FS_SYNC		= 0x200
+	V9FS_PROTO_2000U    = 0x01,
+	V9FS_PROTO_2000L    = 0x02,
+	V9FS_ACCESS_SINGLE  = 0x04,
+	V9FS_ACCESS_USER    = 0x08,
+	V9FS_ACCESS_CLIENT  = 0x10,
+	V9FS_POSIX_ACL      = 0x20,
+	V9FS_NO_XATTR       = 0x40,
+	V9FS_IGNORE_QV      = 0x80, /* ignore qid.version for cache hints */
+	V9FS_DIRECT_IO      = 0x100,
+	V9FS_SYNC           = 0x200
 };
 
-/* possible values of ->cache */
 /**
- * enum p9_cache_modes - user specified cache preferences
- * @CACHE_NONE: do not cache data, dentries, or directory contents (default)
- * @CACHE_LOOSE: cache data, dentries, and directory contents w/no consistency
+ * enum p9_cache_shortcuts - human readable cache preferences
+ * @CACHE_SC_NONE: disable all caches
+ * @CACHE_SC_READAHEAD: only provide caching for readahead
+ * @CACHE_SC_MMAP: provide caching to enable mmap
+ * @CACHE_SC_LOOSE: non-coherent caching for files and meta data
+ * @CACHE_SC_FSCACHE: persistent non-coherent caching for files and meta-data
  *
- * eventually support loose, tight, time, session, default always none
  */
 
-enum p9_cache_modes {
-	CACHE_NONE,
-	CACHE_READAHEAD,
-	CACHE_WRITEBACK,
-	CACHE_MMAP,
-	CACHE_LOOSE,
-	CACHE_FSCACHE,
-	nr__p9_cache_modes
+enum p9_cache_shortcuts {
+	CACHE_SC_NONE       = 0b00000000,
+	CACHE_SC_READAHEAD  = 0b00000001,
+	CACHE_SC_MMAP       = 0b00000101,
+	CACHE_SC_LOOSE      = 0b00001111,
+	CACHE_SC_FSCACHE    = 0b10001111,
+};
+
+/**
+ * enum p9_cache_bits - possible values of ->cache
+ * @CACHE_NONE: caches disabled
+ * @CACHE_FILE: file caching (open to close)
+ * @CACHE_META: meta-data and directory caching
+ * @CACHE_WRITEBACK: write-back caching for files
+ * @CACHE_LOOSE: don't check cache consistency
+ * @CACHE_FSCACHE: local persistent caches
+ *
+ */
+
+enum p9_cache_bits {
+	CACHE_NONE          = 0b00000000,
+	CACHE_FILE          = 0b00000001,
+	CACHE_META          = 0b00000010,
+	CACHE_WRITEBACK     = 0b00000100,
+	CACHE_LOOSE         = 0b00001000,
+	CACHE_FSCACHE       = 0b10000000,
 };
 
 /**
@@ -68,7 +87,7 @@ enum p9_cache_modes {
  * @nodev: set to 1 to disable device mapping
  * @debug: debug level
  * @afid: authentication handle
- * @cache: cache mode of type &p9_cache_modes
+ * @cache: cache mode of type &p9_cache_bits
  * @cachetag: the tag of the cache associated with this session
  * @fscache: session cookie associated with FS-Cache
  * @uname: string user name to mount hierarchy as
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 211165430a8a..193e898093cd 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -115,8 +115,6 @@ const struct netfs_request_ops v9fs_req_ops = {
 
 static bool v9fs_release_folio(struct folio *folio, gfp_t gfp)
 {
-	struct inode *inode = folio_inode(folio);
-
 	if (folio_test_private(folio))
 		return false;
 #ifdef CONFIG_9P_FSCACHE
@@ -125,8 +123,8 @@ static bool v9fs_release_folio(struct folio *folio, gfp_t gfp)
 			return false;
 		folio_wait_fscache(folio);
 	}
+	fscache_note_page_release(v9fs_inode_cookie(V9FS_I(folio_inode(folio))));
 #endif
-	fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode)));
 	return true;
 }
 
@@ -136,6 +134,7 @@ static void v9fs_invalidate_folio(struct folio *folio, size_t offset,
 	folio_wait_fscache(folio);
 }
 
+#ifdef CONFIG_9P_FSCACHE
 static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
 				     bool was_async)
 {
@@ -149,12 +148,11 @@ static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
 				   i_size_read(&v9inode->netfs.inode), 0);
 	}
 }
+#endif
 
 static int v9fs_vfs_write_folio_locked(struct folio *folio)
 {
 	struct inode *inode = folio_inode(folio);
-	struct v9fs_inode *v9inode = V9FS_I(inode);
-	struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode);
 	loff_t start = folio_pos(folio);
 	loff_t i_size = i_size_read(inode);
 	struct iov_iter from;
@@ -181,15 +179,22 @@ static int v9fs_vfs_write_folio_locked(struct folio *folio)
 
 	p9_client_write(writeback_fid, start, &from, &err);
 
-	if (err == 0 &&
-	    fscache_cookie_enabled(cookie) &&
-	    test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) {
-		folio_start_fscache(folio);
-		fscache_write_to_cache(v9fs_inode_cookie(v9inode),
-				       folio_mapping(folio), start, len, i_size,
-				       v9fs_write_to_cache_done, v9inode,
-				       true);
+#ifdef CONFIG_9P_FSCACHE
+	{
+		struct v9fs_inode *v9inode = V9FS_I(inode);
+		struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode);
+
+		if (err == 0 &&
+			fscache_cookie_enabled(cookie) &&
+			test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) {
+			folio_start_fscache(folio);
+			fscache_write_to_cache(v9fs_inode_cookie(v9inode),
+						folio_mapping(folio), start, len, i_size,
+						v9fs_write_to_cache_done, v9inode,
+						true);
+		}
 	}
+#endif
 
 	folio_end_writeback(folio);
 	p9_fid_put(writeback_fid);
@@ -300,7 +305,6 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 	loff_t last_pos = pos + copied;
 	struct folio *folio = page_folio(subpage);
 	struct inode *inode = mapping->host;
-	struct v9fs_inode *v9inode = V9FS_I(inode);
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
@@ -320,7 +324,10 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 	if (last_pos > inode->i_size) {
 		inode_add_bytes(inode, last_pos - inode->i_size);
 		i_size_write(inode, last_pos);
-		fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos);
+#ifdef CONFIG_9P_FSCACHE
+		fscache_update_cookie(v9fs_inode_cookie(V9FS_I(inode)), NULL,
+			&last_pos);
+#endif
 	}
 	folio_mark_dirty(folio);
 out:
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 9f1d464bc1b5..581d2a3a037a 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -60,7 +60,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 		if (IS_ERR(fid))
 			return PTR_ERR(fid);
 
-		if ((v9ses->cache >= CACHE_WRITEBACK) && (omode & P9_OWRITE)) {
+		if ((v9ses->cache & CACHE_WRITEBACK) && (omode & P9_OWRITE)) {
 			int writeback_omode = (omode & ~P9_OWRITE) | P9_ORDWR;
 
 			p9_debug(P9_DEBUG_CACHE, "write-only file with writeback enabled, try opening O_RDWR\n");
@@ -85,7 +85,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 	}
 
 #ifdef CONFIG_9P_FSCACHE
-	if (v9ses->cache == CACHE_FSCACHE)
+	if (v9ses->cache & CACHE_FSCACHE)
 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
 				   file->f_mode & FMODE_WRITE);
 #endif
@@ -485,7 +485,7 @@ v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 
 	p9_debug(P9_DEBUG_MMAP, "filp :%p\n", filp);
 
-	if (v9ses->cache < CACHE_MMAP) {
+	if (!(v9ses->cache & CACHE_WRITEBACK)) {
 		p9_debug(P9_DEBUG_CACHE, "(no mmap mode)");
 		if (vma->vm_flags & VM_MAYSHARE)
 			return -ENODEV;
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index fb5e5c0e41e4..5d106cbcdf25 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -376,12 +376,18 @@ void v9fs_evict_inode(struct inode *inode)
 
 	truncate_inode_pages_final(&inode->i_data);
 	version = cpu_to_le32(v9inode->qid.version);
+
+#ifdef CONFIG_9P_FSCACHE
 	fscache_clear_inode_writeback(v9fs_inode_cookie(v9inode), inode,
 				      &version);
+#endif
+
 	clear_inode(inode);
 	filemap_fdatawrite(&inode->i_data);
 
+#ifdef CONFIG_9P_FSCACHE
 	fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
+#endif
 }
 
 static int v9fs_test_inode(struct inode *inode, void *data)
@@ -761,7 +767,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 		inode = NULL;
 	else if (IS_ERR(fid))
 		inode = ERR_CAST(fid);
-	else if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+	else if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
 	else
 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
@@ -816,7 +822,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	perm = unixmode2p9mode(v9ses, mode);
 	p9_omode = v9fs_uflags2omode(flags, v9fs_proto_dotu(v9ses));
 
-	if ((v9ses->cache >= CACHE_WRITEBACK) && (p9_omode & P9_OWRITE)) {
+	if ((v9ses->cache & CACHE_WRITEBACK) && (p9_omode & P9_OWRITE)) {
 		p9_omode = (p9_omode & !P9_OWRITE) | P9_ORDWR;
 		p9_debug(P9_DEBUG_CACHE,
 			"write-only file with writeback enabled, creating w/ O_RDWR\n");
@@ -835,9 +841,11 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		goto error;
 
 	file->private_data = fid;
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+#ifdef CONFIG_9P_FSCACHE
+	if (v9ses->cache & CACHE_FSCACHE)
 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
 				   file->f_mode & FMODE_WRITE);
+#endif
 
 	v9fs_fid_add_modes(fid, v9ses->flags, v9ses->cache, file->f_flags);
 	v9fs_open_fid_add(inode, &fid);
@@ -1008,10 +1016,10 @@ v9fs_vfs_getattr(struct mnt_idmap *idmap, const struct path *path,
 
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
 	v9ses = v9fs_dentry2v9ses(dentry);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
 		generic_fillattr(&nop_mnt_idmap, inode, stat);
 		return 0;
-	} else if (v9ses->cache >= CACHE_WRITEBACK) {
+	} else if (v9ses->cache & CACHE_WRITEBACK) {
 		if (S_ISREG(inode->i_mode)) {
 			int retval = filemap_fdatawrite(inode->i_mapping);
 
@@ -1050,7 +1058,6 @@ static int v9fs_vfs_setattr(struct mnt_idmap *idmap,
 {
 	int retval, use_dentry = 0;
 	struct inode *inode = d_inode(dentry);
-	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid = NULL;
 	struct p9_wstat wstat;
@@ -1115,8 +1122,13 @@ static int v9fs_vfs_setattr(struct mnt_idmap *idmap,
 		truncate_setsize(inode, iattr->ia_size);
 		truncate_pagecache(inode, iattr->ia_size);
 
-		if (v9ses->cache == CACHE_FSCACHE)
+#ifdef CONFIG_9P_FSCACHE
+		if (v9ses->cache & CACHE_FSCACHE) {
+			struct v9fs_inode *v9inode = V9FS_I(inode);
+
 			fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+		}
+#endif
 	}
 
 	v9fs_invalidate_inode_attr(inode);
@@ -1400,7 +1412,7 @@ int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
 	 * We don't want to refresh inode->i_size,
 	 * because we may have cached data
 	 */
-	flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
+	flags = (v9ses->cache & CACHE_LOOSE) ?
 		V9FS_STAT2INODE_KEEP_ISIZE : 0;
 	v9fs_stat2inode(st, inode, inode->i_sb, flags);
 out:
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 4b9488cb7a56..a1c7dae6795c 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -287,7 +287,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 		goto out;
 	}
 
-	if ((v9ses->cache >= CACHE_WRITEBACK) && (p9_omode & P9_OWRITE)) {
+	if ((v9ses->cache & CACHE_WRITEBACK) && (p9_omode & P9_OWRITE)) {
 		p9_omode = (p9_omode & !P9_OWRITE) | P9_ORDWR;
 		p9_debug(P9_DEBUG_CACHE,
 			"write-only file with writeback enabled, creating w/ O_RDWR\n");
@@ -325,7 +325,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 		goto out;
 	file->private_data = ofid;
 #ifdef CONFIG_9P_FSCACHE
-	if (v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & CACHE_FSCACHE) {
 		struct v9fs_inode *v9inode = V9FS_I(inode);
 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
 				   file->f_mode & FMODE_WRITE);
@@ -403,7 +403,7 @@ static int v9fs_vfs_mkdir_dotl(struct mnt_idmap *idmap,
 	}
 
 	/* instantiate inode and assign the unopened fid to the dentry */
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
 		if (IS_ERR(inode)) {
 			err = PTR_ERR(inode);
@@ -451,7 +451,7 @@ v9fs_vfs_getattr_dotl(struct mnt_idmap *idmap,
 
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
 	v9ses = v9fs_dentry2v9ses(dentry);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
 		generic_fillattr(&nop_mnt_idmap, inode, stat);
 		return 0;
 	} else if (v9ses->cache) {
@@ -538,7 +538,6 @@ int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 {
 	int retval, use_dentry = 0;
 	struct inode *inode = d_inode(dentry);
-	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid = NULL;
 	struct p9_iattr_dotl p9attr = {
@@ -603,8 +602,11 @@ int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 		truncate_setsize(inode, iattr->ia_size);
 		truncate_pagecache(inode, iattr->ia_size);
 
-		if (v9ses->cache == CACHE_FSCACHE)
-			fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+#ifdef CONFIG_9P_FSCACHE
+		if (v9ses->cache & CACHE_FSCACHE)
+			fscache_resize_cookie(v9fs_inode_cookie(V9FS_I(inode)),
+				iattr->ia_size);
+#endif
 	}
 
 	v9fs_invalidate_inode_attr(inode);
@@ -732,7 +734,7 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir,
 	}
 
 	v9fs_invalidate_inode_attr(dir);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
 		/* Now walk from the parent so we can get an unopened fid. */
 		fid = p9_client_walk(dfid, 1, &name, 1);
 		if (IS_ERR(fid)) {
@@ -809,7 +811,7 @@ v9fs_vfs_link_dotl(struct dentry *old_dentry, struct inode *dir,
 	}
 
 	v9fs_invalidate_inode_attr(dir);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
 		/* Get the latest stat info from server. */
 		struct p9_fid *fid;
 
@@ -886,7 +888,7 @@ v9fs_vfs_mknod_dotl(struct mnt_idmap *idmap, struct inode *dir,
 	}
 
 	/* instantiate inode and assign the unopened fid to the dentry */
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
 		if (IS_ERR(inode)) {
 			err = PTR_ERR(inode);
@@ -971,7 +973,7 @@ int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
 	 * We don't want to refresh inode->i_size,
 	 * because we may have cached data
 	 */
-	flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
+	flags = (v9ses->cache & CACHE_LOOSE) ?
 		V9FS_STAT2INODE_KEEP_ISIZE : 0;
 	v9fs_stat2inode_dotl(st, inode, flags);
 out:
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index af83b39e340c..c6cbc666a4c1 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -136,7 +136,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
 	if (retval)
 		goto release_sb;
 
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
 		sb->s_d_op = &v9fs_cached_dentry_operations;
 	else
 		sb->s_d_op = &v9fs_dentry_operations;
@@ -277,7 +277,7 @@ static int v9fs_drop_inode(struct inode *inode)
 	struct v9fs_session_info *v9ses;
 
 	v9ses = v9fs_inode2v9ses(inode);
-	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
 		return generic_drop_inode(inode);
 	/*
 	 * in case of non cached mode always drop the

---
base-commit: 1543b4c5071c54d76aad7a7a26a6e43082269b0c
change-id: 20230401-ericvh-dev-rework-cache-options-2c6638bea240

Best regards,
-- 
Eric Van Hensbergen <ericvh@kernel.org>