fs/9p: Consolidate file operations and add readahead and writeback

We had 3 different sets of file operations across 2 different protocol
variants differentiated by cache which really only changed 3
functions.  But the real problem is that certain file modes, mount
options, and other factors weren't being considered when we
decided whether or not to use caches.

This consolidates all the operations and switches
to conditionals within a common set to decide whether or not
to do different aspects of caching.

Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>

7 files changed, 89 insertions, 162 deletions

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 61a51b90600d..a46bf9121f11 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -39,8 +39,6 @@ enum {
 	Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
 	/* Options that take no arguments */
 	Opt_nodevmap,
-	/* Cache options */
-	Opt_cache_loose, Opt_fscache, Opt_mmap,
 	/* Access options */
 	Opt_access, Opt_posixacl,
 	/* Lock timeout option */
@@ -58,9 +56,6 @@ static const match_table_t tokens = {
 	{Opt_remotename, "aname=%s"},
 	{Opt_nodevmap, "nodevmap"},
 	{Opt_cache, "cache=%s"},
-	{Opt_cache_loose, "loose"},
-	{Opt_fscache, "fscache"},
-	{Opt_mmap, "mmap"},
 	{Opt_cachetag, "cachetag=%s"},
 	{Opt_access, "access=%s"},
 	{Opt_posixacl, "posixacl"},
@@ -69,10 +64,12 @@ static const match_table_t tokens = {
 };
 
 static const char *const v9fs_cache_modes[nr__p9_cache_modes] = {
-	[CACHE_NONE]	= "none",
-	[CACHE_MMAP]	= "mmap",
-	[CACHE_LOOSE]	= "loose",
-	[CACHE_FSCACHE]	= "fscache",
+	[CACHE_NONE]		= "none",
+	[CACHE_READAHEAD]	= "readahead",
+	[CACHE_WRITEBACK]	= "writeback",
+	[CACHE_MMAP]		= "mmap",
+	[CACHE_LOOSE]		= "loose",
+	[CACHE_FSCACHE]		= "fscache",
 };
 
 /* Interpret mount options for cache mode */
@@ -89,6 +86,12 @@ static int get_cache_mode(char *s)
 	} else if (!strcmp(s, "mmap")) {
 		version = CACHE_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;
+		p9_debug(P9_DEBUG_9P, "Cache mode: readahead\n");
 	} else if (!strcmp(s, "none")) {
 		version = CACHE_NONE;
 		p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
@@ -266,15 +269,6 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
 		case Opt_nodevmap:
 			v9ses->nodev = 1;
 			break;
-		case Opt_cache_loose:
-			v9ses->cache = CACHE_LOOSE;
-			break;
-		case Opt_fscache:
-			v9ses->cache = CACHE_FSCACHE;
-			break;
-		case Opt_mmap:
-			v9ses->cache = CACHE_MMAP;
-			break;
 		case Opt_cachetag:
 #ifdef CONFIG_9P_FSCACHE
 			kfree(v9ses->cachetag);
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index f3f74d197b5d..e5d41804b3cd 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -50,6 +50,8 @@ enum p9_session_flags {
 
 enum p9_cache_modes {
 	CACHE_NONE,
+	CACHE_READAHEAD,
+	CACHE_WRITEBACK,
 	CACHE_MMAP,
 	CACHE_LOOSE,
 	CACHE_FSCACHE,
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index 75106b9f293d..cdf441f22e07 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -36,10 +36,6 @@ extern const struct file_operations v9fs_dir_operations;
 extern const struct file_operations v9fs_dir_operations_dotl;
 extern const struct dentry_operations v9fs_dentry_operations;
 extern const struct dentry_operations v9fs_cached_dentry_operations;
-extern const struct file_operations v9fs_cached_file_operations;
-extern const struct file_operations v9fs_cached_file_operations_dotl;
-extern const struct file_operations v9fs_mmap_file_operations;
-extern const struct file_operations v9fs_mmap_file_operations_dotl;
 extern struct kmem_cache *v9fs_inode_cache;
 
 struct inode *v9fs_alloc_inode(struct super_block *sb);
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 3d74b04fe0de..289b58cb896e 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -197,9 +197,9 @@ static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 
 
 /**
- * v9fs_dir_release - called on a close of a file or directory
- * @inode: inode of the directory
- * @filp: file pointer to a directory
+ * v9fs_dir_release - close a directory or a file
+ * @inode: inode of the directory or file
+ * @filp: file pointer to a directory or file
  *
  */
 
@@ -214,7 +214,11 @@ int v9fs_dir_release(struct inode *inode, struct file *filp)
 	fid = filp->private_data;
 	p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 		 inode, filp, fid ? fid->fid : -1);
+
 	if (fid) {
+		if ((S_ISREG(inode->i_mode)) && (filp->f_mode & FMODE_WRITE))
+			retval = filemap_fdatawrite(inode->i_mapping);
+
 		spin_lock(&inode->i_lock);
 		hlist_del(&fid->ilist);
 		spin_unlock(&inode->i_lock);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 44c15eb2b908..cd1f3f4079d7 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -29,7 +29,6 @@
 #include "fid.h"
 #include "cache.h"
 
-static const struct vm_operations_struct v9fs_file_vm_ops;
 static const struct vm_operations_struct v9fs_mmap_file_vm_ops;
 
 /**
@@ -74,7 +73,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 	}
 
 	mutex_lock(&v9inode->v_mutex);
-	if ((v9ses->cache) && !v9inode->writeback_fid &&
+	if ((v9ses->cache >= CACHE_WRITEBACK) && !v9inode->writeback_fid &&
 	    ((file->f_flags & O_ACCMODE) != O_RDONLY)) {
 		/*
 		 * clone a fid and add it to writeback_fid
@@ -368,10 +367,15 @@ v9fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct p9_fid *fid = iocb->ki_filp->private_data;
 	int ret, err = 0;
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
 
 	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n",
 		 iov_iter_count(to), iocb->ki_pos);
 
+	if (v9ses->cache > CACHE_MMAP)
+		return generic_file_read_iter(iocb, to);
+
 	if (iocb->ki_filp->f_flags & O_NONBLOCK)
 		ret = p9_client_read_once(fid, iocb->ki_pos, to, &err);
 	else
@@ -396,6 +400,11 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ssize_t retval;
 	loff_t origin;
 	int err = 0;
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
+
+	if (v9ses->cache >= CACHE_WRITEBACK)
+		return generic_file_write_iter(iocb, from);
 
 	retval = generic_write_checks(iocb, from);
 	if (retval <= 0)
@@ -478,25 +487,16 @@ static int
 v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	int retval;
-
-
-	retval = generic_file_mmap(filp, vma);
-	if (!retval)
-		vma->vm_ops = &v9fs_file_vm_ops;
-
-	return retval;
-}
-
-static int
-v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma)
-{
-	int retval;
-	struct inode *inode;
-	struct v9fs_inode *v9inode;
+	struct inode *inode = file_inode(filp);
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
 	struct p9_fid *fid;
 
-	inode = file_inode(filp);
-	v9inode = V9FS_I(inode);
+	if (v9ses->cache < CACHE_MMAP) {
+		invalidate_inode_pages2(filp->f_mapping);
+		return generic_file_readonly_mmap(filp, vma);
+	}
+
 	mutex_lock(&v9inode->v_mutex);
 	if (!v9inode->writeback_fid &&
 	    (vma->vm_flags & VM_SHARED) &&
@@ -564,35 +564,6 @@ out_unlock:
 	return VM_FAULT_NOPAGE;
 }
 
-/**
- * v9fs_mmap_file_read_iter - read from a file
- * @iocb: The operation parameters
- * @to: The buffer to read into
- *
- */
-static ssize_t
-v9fs_mmap_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
-{
-	/* TODO: Check if there are dirty pages */
-	return v9fs_file_read_iter(iocb, to);
-}
-
-/**
- * v9fs_mmap_file_write_iter - write to a file
- * @iocb: The operation parameters
- * @from: The data to write
- *
- */
-static ssize_t
-v9fs_mmap_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
-	/*
-	 * TODO: invalidate mmaps on filp's inode between
-	 * offset and offset+count
-	 */
-	return v9fs_file_write_iter(iocb, from);
-}
-
 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
 {
 	struct inode *inode;
@@ -615,13 +586,6 @@ static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
 	filemap_fdatawrite_wbc(inode->i_mapping, &wbc);
 }
 
-
-static const struct vm_operations_struct v9fs_file_vm_ops = {
-	.fault = filemap_fault,
-	.map_pages = filemap_map_pages,
-	.page_mkwrite = v9fs_vm_page_mkwrite,
-};
-
 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
 	.close = v9fs_mmap_vm_close,
 	.fault = filemap_fault,
@@ -629,34 +593,6 @@ static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
 	.page_mkwrite = v9fs_vm_page_mkwrite,
 };
 
-
-const struct file_operations v9fs_cached_file_operations = {
-	.llseek = generic_file_llseek,
-	.read_iter = generic_file_read_iter,
-	.write_iter = generic_file_write_iter,
-	.open = v9fs_file_open,
-	.release = v9fs_dir_release,
-	.lock = v9fs_file_lock,
-	.mmap = v9fs_file_mmap,
-	.splice_read = generic_file_splice_read,
-	.splice_write = iter_file_splice_write,
-	.fsync = v9fs_file_fsync,
-};
-
-const struct file_operations v9fs_cached_file_operations_dotl = {
-	.llseek = generic_file_llseek,
-	.read_iter = generic_file_read_iter,
-	.write_iter = generic_file_write_iter,
-	.open = v9fs_file_open,
-	.release = v9fs_dir_release,
-	.lock = v9fs_file_lock_dotl,
-	.flock = v9fs_file_flock_dotl,
-	.mmap = v9fs_file_mmap,
-	.splice_read = generic_file_splice_read,
-	.splice_write = iter_file_splice_write,
-	.fsync = v9fs_file_fsync_dotl,
-};
-
 const struct file_operations v9fs_file_operations = {
 	.llseek = generic_file_llseek,
 	.read_iter = v9fs_file_read_iter,
@@ -678,34 +614,7 @@ const struct file_operations v9fs_file_operations_dotl = {
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock_dotl,
 	.flock = v9fs_file_flock_dotl,
-	.mmap = generic_file_readonly_mmap,
-	.splice_read = generic_file_splice_read,
-	.splice_write = iter_file_splice_write,
-	.fsync = v9fs_file_fsync_dotl,
-};
-
-const struct file_operations v9fs_mmap_file_operations = {
-	.llseek = generic_file_llseek,
-	.read_iter = v9fs_mmap_file_read_iter,
-	.write_iter = v9fs_mmap_file_write_iter,
-	.open = v9fs_file_open,
-	.release = v9fs_dir_release,
-	.lock = v9fs_file_lock,
-	.mmap = v9fs_mmap_file_mmap,
-	.splice_read = generic_file_splice_read,
-	.splice_write = iter_file_splice_write,
-	.fsync = v9fs_file_fsync,
-};
-
-const struct file_operations v9fs_mmap_file_operations_dotl = {
-	.llseek = generic_file_llseek,
-	.read_iter = v9fs_mmap_file_read_iter,
-	.write_iter = v9fs_mmap_file_write_iter,
-	.open = v9fs_file_open,
-	.release = v9fs_dir_release,
-	.lock = v9fs_file_lock_dotl,
-	.flock = v9fs_file_flock_dotl,
-	.mmap = v9fs_mmap_file_mmap,
+	.mmap = v9fs_file_mmap,
 	.splice_read = generic_file_splice_read,
 	.splice_write = iter_file_splice_write,
 	.fsync = v9fs_file_fsync_dotl,
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 1d523bec0a94..63590f55363b 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -287,24 +287,10 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses,
 	case S_IFREG:
 		if (v9fs_proto_dotl(v9ses)) {
 			inode->i_op = &v9fs_file_inode_operations_dotl;
-			if (v9ses->cache == CACHE_LOOSE ||
-			    v9ses->cache == CACHE_FSCACHE)
-				inode->i_fop =
-					&v9fs_cached_file_operations_dotl;
-			else if (v9ses->cache == CACHE_MMAP)
-				inode->i_fop = &v9fs_mmap_file_operations_dotl;
-			else
-				inode->i_fop = &v9fs_file_operations_dotl;
+			inode->i_fop = &v9fs_file_operations_dotl;
 		} else {
 			inode->i_op = &v9fs_file_inode_operations;
-			if (v9ses->cache == CACHE_LOOSE ||
-			    v9ses->cache == CACHE_FSCACHE)
-				inode->i_fop =
-					&v9fs_cached_file_operations;
-			else if (v9ses->cache == CACHE_MMAP)
-				inode->i_fop = &v9fs_mmap_file_operations;
-			else
-				inode->i_fop = &v9fs_file_operations;
+			inode->i_fop = &v9fs_file_operations;
 		}
 
 		break;
@@ -843,7 +829,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	inode = d_inode(dentry);
 	v9inode = V9FS_I(inode);
 	mutex_lock(&v9inode->v_mutex);
-	if ((v9ses->cache) && !v9inode->writeback_fid &&
+	if ((v9ses->cache >= CACHE_WRITEBACK) && !v9inode->writeback_fid &&
 	    ((flags & O_ACCMODE) != O_RDONLY)) {
 		/*
 		 * clone a fid and add it to writeback_fid
@@ -1030,6 +1016,7 @@ v9fs_vfs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct dentry *dentry = path->dentry;
+	struct inode *inode = d_inode(dentry);
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid;
 	struct p9_wstat *st;
@@ -1039,6 +1026,14 @@ v9fs_vfs_getattr(struct mnt_idmap *idmap, const struct path *path,
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
 		generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 		return 0;
+	} else if (v9ses->cache >= CACHE_WRITEBACK) {
+		if (S_ISREG(inode->i_mode)) {
+			int retval = filemap_fdatawrite(inode->i_mapping);
+
+			if (retval)
+				p9_debug(P9_DEBUG_ERROR,
+				    "flushing writeback during getattr returned %d\n", retval);
+		}
 	}
 	fid = v9fs_fid_lookup(dentry);
 	if (IS_ERR(fid))
@@ -1115,8 +1110,12 @@ static int v9fs_vfs_setattr(struct mnt_idmap *idmap,
 	}
 
 	/* Write all dirty data */
-	if (d_is_reg(dentry))
-		filemap_write_and_wait(inode->i_mapping);
+	if (d_is_reg(dentry)) {
+		retval = filemap_fdatawrite(inode->i_mapping);
+		if (retval)
+			p9_debug(P9_DEBUG_ERROR,
+			    "flushing writeback during setattr returned %d\n", retval);
+	}
 
 	retval = p9_client_wstat(fid, &wstat);
 
@@ -1127,9 +1126,12 @@ static int v9fs_vfs_setattr(struct mnt_idmap *idmap,
 		return retval;
 
 	if ((iattr->ia_valid & ATTR_SIZE) &&
-	    iattr->ia_size != i_size_read(inode)) {
+		 iattr->ia_size != i_size_read(inode)) {
 		truncate_setsize(inode, iattr->ia_size);
-		fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+		if (v9ses->cache == CACHE_FSCACHE)
+			fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+		else
+			invalidate_mapping_pages(&inode->i_data, 0, -1);
 	}
 
 	v9fs_invalidate_inode_attr(inode);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 331ed60d8fcb..a28eb3aeab29 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -458,6 +458,7 @@ v9fs_vfs_getattr_dotl(struct mnt_idmap *idmap,
 	struct dentry *dentry = path->dentry;
 	struct v9fs_session_info *v9ses;
 	struct p9_fid *fid;
+	struct inode *inode = d_inode(dentry);
 	struct p9_stat_dotl *st;
 
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
@@ -465,6 +466,14 @@ v9fs_vfs_getattr_dotl(struct mnt_idmap *idmap,
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
 		generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 		return 0;
+	} else if (v9ses->cache >= CACHE_WRITEBACK) {
+		if (S_ISREG(inode->i_mode)) {
+			int retval = filemap_fdatawrite(inode->i_mapping);
+
+			if (retval)
+				p9_debug(P9_DEBUG_ERROR,
+				    "flushing writeback during getattr returned %d\n", retval);
+		}
 	}
 	fid = v9fs_fid_lookup(dentry);
 	if (IS_ERR(fid))
@@ -540,12 +549,14 @@ int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 			  struct dentry *dentry, struct iattr *iattr)
 {
 	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 = {
 		.uid = INVALID_UID,
 		.gid = INVALID_GID,
 	};
-	struct inode *inode = d_inode(dentry);
 
 	p9_debug(P9_DEBUG_VFS, "\n");
 
@@ -553,6 +564,8 @@ int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 	if (retval)
 		return retval;
 
+	v9ses = v9fs_dentry2v9ses(dentry);
+
 	p9attr.valid = v9fs_mapped_iattr_valid(iattr->ia_valid);
 	if (iattr->ia_valid & ATTR_MODE)
 		p9attr.mode = iattr->ia_mode;
@@ -583,8 +596,12 @@ int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 		return PTR_ERR(fid);
 
 	/* Write all dirty data */
-	if (S_ISREG(inode->i_mode))
-		filemap_write_and_wait(inode->i_mapping);
+	if (S_ISREG(inode->i_mode)) {
+		retval = filemap_fdatawrite(inode->i_mapping);
+		if (retval < 0)
+			p9_debug(P9_DEBUG_ERROR,
+			    "Flushing file prior to setattr failed: %d\n", retval);
+	}
 
 	retval = p9_client_setattr(fid, &p9attr);
 	if (retval < 0) {
@@ -593,9 +610,12 @@ int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
 		return retval;
 	}
 
-	if ((iattr->ia_valid & ATTR_SIZE) &&
-	    iattr->ia_size != i_size_read(inode))
+	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size !=
+		 i_size_read(inode)) {
 		truncate_setsize(inode, iattr->ia_size);
+		if (v9ses->cache == CACHE_FSCACHE)
+			fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+	}
 
 	v9fs_invalidate_inode_attr(inode);
 	setattr_copy(&nop_mnt_idmap, inode, iattr);