switch generic_write_checks() to iocb and iter

... returning -E... upon error and amount of data left in iter after
(possible) truncation upon success.  Note, that normal case gives
a non-zero (positive) return value, so any tests for != 0 _must_ be
updated.

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

Conflicts:
	fs/ext4/file.c

1 files changed, 7 insertions, 15 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 8c15d0a077e8..b86c8e08399a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1145,13 +1145,11 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
         struct file *file = iocb->ki_filp;
         struct address_space *mapping = file->f_mapping;
-        size_t count = iov_iter_count(from);
         ssize_t written = 0;
         ssize_t written_buffered = 0;
         struct inode *inode = mapping->host;
         ssize_t err;
         loff_t endbyte = 0;
-        loff_t pos = iocb->ki_pos;
 
         if (get_fuse_conn(inode)->writeback_cache) {
                 /* Update size (EOF optimization) and mode (SUID clearing) */
@@ -1167,14 +1165,10 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
         /* We can write back this queue in page reclaim */
         current->backing_dev_info = inode_to_bdi(inode);
 
-        err = generic_write_checks(file, &pos, &count);
-        if (err)
-                goto out;
-
-        if (count == 0)
+        err = generic_write_checks(iocb, from);
+        if (err <= 0)
                 goto out;
 
-        iov_iter_truncate(from, count);
         err = file_remove_suid(file);
         if (err)
                 goto out;
@@ -1184,6 +1178,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
                 goto out;
 
         if (file->f_flags & O_DIRECT) {
+                loff_t pos = iocb->ki_pos;
                 written = generic_file_direct_write(iocb, from, pos);
                 if (written < 0 || !iov_iter_count(from))
                         goto out;
@@ -1209,9 +1204,9 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
                 written += written_buffered;
                 iocb->ki_pos = pos + written_buffered;
         } else {
-                written = fuse_perform_write(file, mapping, from, pos);
+                written = fuse_perform_write(file, mapping, from, iocb->ki_pos);
                 if (written >= 0)
-                        iocb->ki_pos = pos + written;
+                        iocb->ki_pos += written;
         }
 out:
         current->backing_dev_info = NULL;
@@ -1412,7 +1407,6 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
         struct file *file = iocb->ki_filp;
         struct inode *inode = file_inode(file);
         struct fuse_io_priv io = { .async = 0, .file = file };
-        size_t count = iov_iter_count(from);
         ssize_t res;
 
         if (is_bad_inode(inode))
@@ -1420,11 +1414,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
         /* Don't allow parallel writes to the same file */
         mutex_lock(&inode->i_mutex);
-        res = generic_write_checks(file, &iocb->ki_pos, &count);
-        if (!res) {
-                iov_iter_truncate(from, count);
+        res = generic_write_checks(iocb, from);
+        if (res > 0)
                 res = fuse_direct_io(&io, from, &iocb->ki_pos, FUSE_DIO_WRITE);
-        }
         fuse_invalidate_attr(inode);
         if (res > 0)
                 fuse_write_update_size(inode, iocb->ki_pos);