fuse: pull iov_iter initializations up

... to fuse_direct_{read,write}().  ->direct_IO() path uses the
iov_iter passed by the caller instead.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 38 insertions, 30 deletions

diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index 13b691a8a7d2..966ace8b243f 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -94,8 +94,10 @@ static ssize_t cuse_read(struct file *file, char __user *buf, size_t count,
         loff_t pos = 0;
         struct iovec iov = { .iov_base = buf, .iov_len = count };
         struct fuse_io_priv io = { .async = 0, .file = file };
+        struct iov_iter ii;
+        iov_iter_init(&ii, READ, &iov, 1, count);
 
-        return fuse_direct_io(&io, &iov, 1, count, &pos, FUSE_DIO_CUSE);
+        return fuse_direct_io(&io, &ii, &pos, FUSE_DIO_CUSE);
 }
 
 static ssize_t cuse_write(struct file *file, const char __user *buf,
@@ -104,12 +106,14 @@ static ssize_t cuse_write(struct file *file, const char __user *buf,
         loff_t pos = 0;
         struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
         struct fuse_io_priv io = { .async = 0, .file = file };
+        struct iov_iter ii;
+        iov_iter_init(&ii, WRITE, &iov, 1, count);
 
         /*
          * No locking or generic_write_checks(), the server is
          * responsible for locking and sanity checks.
          */
-        return fuse_direct_io(&io, &iov, 1, count, &pos,
+        return fuse_direct_io(&io, &ii, &pos,
                               FUSE_DIO_WRITE | FUSE_DIO_CUSE);
 }
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4a5519ca253f..10e9fcd8fe55 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1368,9 +1368,8 @@ static inline int fuse_iter_npages(const struct iov_iter *ii_p)
         return min(npages, FUSE_MAX_PAGES_PER_REQ);
 }
 
-ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
-                       unsigned long nr_segs, size_t count, loff_t *ppos,
-                       int flags)
+ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
+                       loff_t *ppos, int flags)
 {
         int write = flags & FUSE_DIO_WRITE;
         int cuse = flags & FUSE_DIO_CUSE;
@@ -1380,18 +1379,16 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
         struct fuse_conn *fc = ff->fc;
         size_t nmax = write ? fc->max_write : fc->max_read;
         loff_t pos = *ppos;
+        size_t count = iov_iter_count(iter);
         pgoff_t idx_from = pos >> PAGE_CACHE_SHIFT;
         pgoff_t idx_to = (pos + count - 1) >> PAGE_CACHE_SHIFT;
         ssize_t res = 0;
         struct fuse_req *req;
-        struct iov_iter ii;
-
-        iov_iter_init(&ii, write ? WRITE : READ, iov, nr_segs, count);
 
         if (io->async)
-                req = fuse_get_req_for_background(fc, fuse_iter_npages(&ii));
+                req = fuse_get_req_for_background(fc, fuse_iter_npages(iter));
         else
-                req = fuse_get_req(fc, fuse_iter_npages(&ii));
+                req = fuse_get_req(fc, fuse_iter_npages(iter));
         if (IS_ERR(req))
                 return PTR_ERR(req);
 
@@ -1407,7 +1404,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
                 size_t nres;
                 fl_owner_t owner = current->files;
                 size_t nbytes = min(count, nmax);
-                int err = fuse_get_user_pages(req, &ii, &nbytes, write);
+                int err = fuse_get_user_pages(req, iter, &nbytes, write);
                 if (err) {
                         res = err;
                         break;
@@ -1437,9 +1434,9 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
                         fuse_put_request(fc, req);
                         if (io->async)
                                 req = fuse_get_req_for_background(fc,
-                                        fuse_iter_npages(&ii));
+                                        fuse_iter_npages(iter));
                         else
-                                req = fuse_get_req(fc, fuse_iter_npages(&ii));
+                                req = fuse_get_req(fc, fuse_iter_npages(iter));
                         if (IS_ERR(req))
                                 break;
                 }
@@ -1454,9 +1451,8 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
 EXPORT_SYMBOL_GPL(fuse_direct_io);
 
 static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
-                                  const struct iovec *iov,
-                                  unsigned long nr_segs, loff_t *ppos,
-                                  size_t count)
+                                  struct iov_iter *iter,
+                                  loff_t *ppos)
 {
         ssize_t res;
         struct file *file = io->file;
@@ -1465,7 +1461,7 @@ static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
         if (is_bad_inode(inode))
                 return -EIO;
 
-        res = fuse_direct_io(io, iov, nr_segs, count, ppos, 0);
+        res = fuse_direct_io(io, iter, ppos, 0);
 
         fuse_invalidate_attr(inode);
 
@@ -1477,22 +1473,27 @@ static ssize_t fuse_direct_read(struct file *file, char __user *buf,
 {
         struct fuse_io_priv io = { .async = 0, .file = file };
         struct iovec iov = { .iov_base = buf, .iov_len = count };
-        return __fuse_direct_read(&io, &iov, 1, ppos, count);
+        struct iov_iter ii;
+        iov_iter_init(&ii, READ, &iov, 1, count);
+        return __fuse_direct_read(&io, &ii, ppos);
 }
 
 static ssize_t __fuse_direct_write(struct fuse_io_priv *io,
-                                   const struct iovec *iov,
-                                   unsigned long nr_segs, loff_t *ppos)
+                                   struct iov_iter *iter,
+                                   loff_t *ppos)
 {
         struct file *file = io->file;
         struct inode *inode = file_inode(file);
-        size_t count = iov_length(iov, nr_segs);
+        size_t count = iov_iter_count(iter);
         ssize_t res;
 
+
         res = generic_write_checks(file, ppos, &count, 0);
-        if (!res)
-                res = fuse_direct_io(io, iov, nr_segs, count, ppos,
-                                     FUSE_DIO_WRITE);
+        if (!res) {
+                if (iter->count > count)
+                        iter->count = count;
+                res = fuse_direct_io(io, iter, ppos, FUSE_DIO_WRITE);
+        }
 
         fuse_invalidate_attr(inode);
 
@@ -1506,13 +1507,15 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
         struct inode *inode = file_inode(file);
         ssize_t res;
         struct fuse_io_priv io = { .async = 0, .file = file };
+        struct iov_iter ii;
+        iov_iter_init(&ii, WRITE, &iov, 1, count);
 
         if (is_bad_inode(inode))
                 return -EIO;
 
         /* Don't allow parallel writes to the same file */
         mutex_lock(&inode->i_mutex);
-        res = __fuse_direct_write(&io, &iov, 1, ppos);
+        res = __fuse_direct_write(&io, &ii, ppos);
         if (res > 0)
                 fuse_write_update_size(inode, *ppos);
         mutex_unlock(&inode->i_mutex);
@@ -2914,6 +2917,8 @@ fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
                 if (offset >= i_size)
                         return 0;
                 count = min_t(loff_t, count, fuse_round_up(i_size - offset));
+                if (iter->count > count)
+                        iter->count = count;
         }
 
         io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
@@ -2943,9 +2948,9 @@ fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
                 io->async = false;
 
         if (rw == WRITE)
-                ret = __fuse_direct_write(io, iter->iov, iter->nr_segs, &pos);
+                ret = __fuse_direct_write(io, iter, &pos);
         else
-                ret = __fuse_direct_read(io, iter->iov, iter->nr_segs, &pos, count);
+                ret = __fuse_direct_read(io, iter, &pos);
 
         if (io->async) {
                 fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 7aa5c75e0de1..e8e47a6ab518 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -880,9 +880,8 @@ int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 /** CUSE pass fuse_direct_io() a file which f_mapping->host is not from FUSE */
 #define FUSE_DIO_CUSE  (1 << 1)
 
-ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
-                       unsigned long nr_segs, size_t count, loff_t *ppos,
-                       int flags);
+ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
+                       loff_t *ppos, int flags);
 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
                    unsigned int flags);
 long fuse_ioctl_common(struct file *file, unsigned int cmd,