fuse: categorize fuse_get_req()

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>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

6 files changed, 57 insertions, 45 deletions

diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index e397b675b029..5cc838f320d4 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -419,7 +419,7 @@ 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 af37ae138252..ff5e8bed5d88 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -118,7 +118,7 @@ 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, unsigned npages)
 {
         struct fuse_req *req;
         sigset_t oldset;
@@ -137,7 +137,7 @@ 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);
 
@@ -521,7 +522,7 @@ void fuse_force_forget(struct file *file, u64 nodeid)
 
         memset(&inarg, 0, sizeof(inarg));
         inarg.nlookup = 1;
-        req = fuse_get_req_nofail(fc, file);
+        req = fuse_get_req_nofail_nopages(fc, file);
         req->in.h.opcode = FUSE_FORGET;
         req->in.h.nodeid = nodeid;
         req->in.numargs = 1;
@@ -1577,7 +1578,7 @@ 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 dcc1e522c7d4..d04bcc5cccd0 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);
 
@@ -1305,7 +1305,7 @@ 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);
 
@@ -1349,7 +1349,7 @@ 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))
@@ -1562,7 +1562,7 @@ 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);
 
@@ -1670,7 +1670,7 @@ 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);
 
@@ -1709,7 +1709,7 @@ 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);
 
@@ -1761,7 +1761,7 @@ 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);
 
@@ -1806,7 +1806,7 @@ 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 2565f635c04f..882877125c1d 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;
                 }
@@ -1471,7 +1471,7 @@ 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);
 
@@ -1506,7 +1506,7 @@ 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);
 
@@ -1575,7 +1575,7 @@ 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;
 
@@ -1873,7 +1873,7 @@ 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;
@@ -2076,7 +2076,7 @@ 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;
 
@@ -2194,7 +2194,7 @@ static 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 0c5b9310f930..5b21e6ab9e75 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -683,14 +683,25 @@ struct fuse_req *fuse_request_alloc_nofs(unsigned 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, unsigned 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 9a937f0239e8..9d95a5a3d55c 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -413,7 +413,7 @@ 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);