[PATCH 02/11] fuse: categorize fuse_get_req()

[Maxim Patlasov <mpatlasov@parallels.com>]

The patch categorizes all fuse_get_req() invocations into two categories:
 - fuse_get_req_nopages(fc) - when caller doesn't care about req->pages
 - fuse_get_req(fc, n) - when caller need n page pointers (n > 0)

Adding fuse_get_req_nopages() helps to avoid numerous fuse_get_req(fc, 0)
scattered over code. Now it's clear from the first glance when a caller need
fuse_req with page pointers.

The patch doesn't make any logic changes. In multi-page case, it silly
allocates array of FUSE_MAX_PAGES_PER_REQ page pointers. This will be amended
by future patches.

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
---
 fs/fuse/cuse.c   |    2 +-
 fs/fuse/dev.c    |   11 ++++++-----
 fs/fuse/dir.c    |   38 +++++++++++++++++++-------------------
 fs/fuse/file.c   |   30 +++++++++++++++---------------
 fs/fuse/fuse_i.h |   17 ++++++++++++++---
 fs/fuse/inode.c  |    2 +-
 6 files changed, 56 insertions(+), 44 deletions(-)

diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index 3426521..2f1d5dd 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -411,7 +411,7 @@ static int cuse_send_init(struct cuse_conn *cc)
 
 	BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req(fc, 1);
 	if (IS_ERR(req)) {
 		rc = PTR_ERR(req);
 		goto err;
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 1b5fc73..3ad5570 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -117,7 +117,7 @@ static void fuse_req_init_context(struct fuse_req *req)
 	req->in.h.pid = current->pid;
 }
 
-struct fuse_req *fuse_get_req(struct fuse_conn *fc)
+struct fuse_req *fuse_get_req(struct fuse_conn *fc, int npages)
 {
 	struct fuse_req *req;
 	sigset_t oldset;
@@ -136,7 +136,7 @@ struct fuse_req *fuse_get_req(struct fuse_conn *fc)
 	if (!fc->connected)
 		goto out;
 
-	req = fuse_request_alloc(FUSE_MAX_PAGES_PER_REQ);
+	req = fuse_request_alloc(npages);
 	err = -ENOMEM;
 	if (!req)
 		goto out;
@@ -207,13 +207,14 @@ static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
  * filesystem should not have it's own file open.  If deadlock is
  * intentional, it can still be broken by "aborting" the filesystem.
  */
-struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
+struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
+					     struct file *file)
 {
 	struct fuse_req *req;
 
 	atomic_inc(&fc->num_waiting);
 	wait_event(fc->blocked_waitq, !fc->blocked);
-	req = fuse_request_alloc(FUSE_MAX_PAGES_PER_REQ);
+	req = fuse_request_alloc(0);
 	if (!req)
 		req = get_reserved_req(fc, file);
 
@@ -1563,7 +1564,7 @@ static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
 	unsigned int offset;
 	size_t total_len = 0;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 324bc08..1929bfb 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -178,7 +178,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 			return -ECHILD;
 
 		fc = get_fuse_conn(inode);
-		req = fuse_get_req(fc);
+		req = fuse_get_req_nopages(fc);
 		if (IS_ERR(req))
 			return 0;
 
@@ -271,7 +271,7 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
 	if (name->len > FUSE_NAME_MAX)
 		goto out;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	err = PTR_ERR(req);
 	if (IS_ERR(req))
 		goto out;
@@ -391,7 +391,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
 	if (!forget)
 		goto out_err;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	err = PTR_ERR(req);
 	if (IS_ERR(req))
 		goto out_put_forget_req;
@@ -592,7 +592,7 @@ static int fuse_mknod(struct inode *dir, struct dentry *entry, umode_t mode,
 {
 	struct fuse_mknod_in inarg;
 	struct fuse_conn *fc = get_fuse_conn(dir);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -623,7 +623,7 @@ static int fuse_mkdir(struct inode *dir, struct dentry *entry, umode_t mode)
 {
 	struct fuse_mkdir_in inarg;
 	struct fuse_conn *fc = get_fuse_conn(dir);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -647,7 +647,7 @@ static int fuse_symlink(struct inode *dir, struct dentry *entry,
 {
 	struct fuse_conn *fc = get_fuse_conn(dir);
 	unsigned len = strlen(link) + 1;
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -664,7 +664,7 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 {
 	int err;
 	struct fuse_conn *fc = get_fuse_conn(dir);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -696,7 +696,7 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
 {
 	int err;
 	struct fuse_conn *fc = get_fuse_conn(dir);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -723,7 +723,7 @@ static int fuse_rename(struct inode *olddir, struct dentry *oldent,
 	int err;
 	struct fuse_rename_in inarg;
 	struct fuse_conn *fc = get_fuse_conn(olddir);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 
 	if (IS_ERR(req))
 		return PTR_ERR(req);
@@ -776,7 +776,7 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
 	struct fuse_link_in inarg;
 	struct inode *inode = entry->d_inode;
 	struct fuse_conn *fc = get_fuse_conn(inode);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -848,7 +848,7 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
 	struct fuse_req *req;
 	u64 attr_version;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1029,7 +1029,7 @@ static int fuse_access(struct inode *inode, int mask)
 	if (fc->no_access)
 		return 0;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1167,7 +1167,7 @@ static int fuse_readdir(struct file *file, void *dstbuf, filldir_t filldir)
 	if (is_bad_inode(inode))
 		return -EIO;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req(fc, 1);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1197,7 +1197,7 @@ static char *read_link(struct dentry *dentry)
 {
 	struct inode *inode = dentry->d_inode;
 	struct fuse_conn *fc = get_fuse_conn(inode);
-	struct fuse_req *req = fuse_get_req(fc);
+	struct fuse_req *req = fuse_get_req_nopages(fc);
 	char *link;
 
 	if (IS_ERR(req))
@@ -1410,7 +1410,7 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
 	if (attr->ia_valid & ATTR_SIZE)
 		is_truncate = true;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1518,7 +1518,7 @@ static int fuse_setxattr(struct dentry *entry, const char *name,
 	if (fc->no_setxattr)
 		return -EOPNOTSUPP;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1557,7 +1557,7 @@ static ssize_t fuse_getxattr(struct dentry *entry, const char *name,
 	if (fc->no_getxattr)
 		return -EOPNOTSUPP;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1609,7 +1609,7 @@ static ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
 	if (fc->no_listxattr)
 		return -EOPNOTSUPP;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1654,7 +1654,7 @@ static int fuse_removexattr(struct dentry *entry, const char *name)
 	if (fc->no_removexattr)
 		return -EOPNOTSUPP;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 7423ea4..214e13e 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -25,7 +25,7 @@ static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 	struct fuse_req *req;
 	int err;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -368,7 +368,7 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	if (fc->no_flush)
 		return 0;
 
-	req = fuse_get_req_nofail(fc, file);
+	req = fuse_get_req_nofail_nopages(fc, file);
 	memset(&inarg, 0, sizeof(inarg));
 	inarg.fh = ff->fh;
 	inarg.lock_owner = fuse_lock_owner_id(fc, id);
@@ -436,7 +436,7 @@ int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
 
 	fuse_sync_writes(inode);
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req)) {
 		err = PTR_ERR(req);
 		goto out;
@@ -544,7 +544,7 @@ static int fuse_readpage(struct file *file, struct page *page)
 	 */
 	fuse_wait_on_page_writeback(inode, page->index);
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req(fc, 1);
 	err = PTR_ERR(req);
 	if (IS_ERR(req))
 		goto out;
@@ -657,7 +657,7 @@ static int fuse_readpages_fill(void *_data, struct page *page)
 	     (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 	     req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 		fuse_send_readpages(req, data->file);
-		data->req = req = fuse_get_req(fc);
+		data->req = req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 		if (IS_ERR(req)) {
 			unlock_page(page);
 			return PTR_ERR(req);
@@ -683,7 +683,7 @@ static int fuse_readpages(struct file *file, struct address_space *mapping,
 
 	data.file = file;
 	data.inode = inode;
-	data.req = fuse_get_req(fc);
+	data.req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 	err = PTR_ERR(data.req);
 	if (IS_ERR(data.req))
 		goto out;
@@ -890,7 +890,7 @@ static ssize_t fuse_perform_write(struct file *file,
 		struct fuse_req *req;
 		ssize_t count;
 
-		req = fuse_get_req(fc);
+		req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 		if (IS_ERR(req)) {
 			err = PTR_ERR(req);
 			break;
@@ -1072,7 +1072,7 @@ ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 	ssize_t res = 0;
 	struct fuse_req *req;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1108,7 +1108,7 @@ ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 			break;
 		if (count) {
 			fuse_put_request(fc, req);
-			req = fuse_get_req(fc);
+			req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 			if (IS_ERR(req))
 				break;
 		}
@@ -1470,7 +1470,7 @@ static int fuse_getlk(struct file *file, struct file_lock *fl)
 	struct fuse_lk_out outarg;
 	int err;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1505,7 +1505,7 @@ static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
 	if (fl->fl_flags & FL_CLOSE)
 		return 0;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -1574,7 +1574,7 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
 	if (!inode->i_sb->s_bdev || fc->no_bmap)
 		return 0;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return 0;
 
@@ -1872,7 +1872,7 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 		num_pages++;
 	}
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
 	if (IS_ERR(req)) {
 		err = PTR_ERR(req);
 		req = NULL;
@@ -2075,7 +2075,7 @@ unsigned fuse_file_poll(struct file *file, poll_table *wait)
 		fuse_register_polled_file(fc, ff);
 	}
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return POLLERR;
 
@@ -2193,7 +2193,7 @@ long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 	if (fc->no_fallocate)
 		return -EOPNOTSUPP;
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index e686bf1..fd69d62 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -677,14 +677,25 @@ struct fuse_req *fuse_request_alloc_nofs(int npages);
 void fuse_request_free(struct fuse_req *req);
 
 /**
- * Get a request, may fail with -ENOMEM
+ * Get a request, may fail with -ENOMEM,
+ * caller should specify # elements in req->pages[] explicitly
  */
-struct fuse_req *fuse_get_req(struct fuse_conn *fc);
+struct fuse_req *fuse_get_req(struct fuse_conn *fc, int npages);
+
+/**
+ * Get a request, may fail with -ENOMEM,
+ * useful for callers who doesn't use req->pages[]
+ */
+static inline struct fuse_req *fuse_get_req_nopages(struct fuse_conn *fc)
+{
+	return fuse_get_req(fc, 0);
+}
 
 /**
  * Gets a requests for a file operation, always succeeds
  */
-struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file);
+struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
+					     struct file *file);
 
 /**
  * Decrement reference count of a request.  If count goes to zero free
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 3f399ba..efb6144 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -411,7 +411,7 @@ static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 		return 0;
 	}
 
-	req = fuse_get_req(fc);
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);