iov_iter_truncate()

Now It Can Be Done(tm) - we don't need to do iov_shorten() in
generic_file_direct_write() anymore, now that all ->direct_IO()
instances are converted to proper iov_iter methods and honour
iter->count and iter->iov_offset properly.

Get rid of count/ocount arguments of generic_file_direct_write(),
while we are at it.

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

1 files changed, 8 insertions, 9 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f8cee205618a..ea63a51c148c 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1659,8 +1659,7 @@ again:
 
 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
                                     struct iov_iter *from,
-                                    loff_t pos,
-                                    size_t count, size_t ocount)
+                                    loff_t pos)
 {
         struct file *file = iocb->ki_filp;
         ssize_t written;
@@ -1668,9 +1667,9 @@ static ssize_t __btrfs_direct_write(struct kiocb *iocb,
         loff_t endbyte;
         int err;
 
-        written = generic_file_direct_write(iocb, from, pos, count, ocount);
+        written = generic_file_direct_write(iocb, from, pos);
 
-        if (written < 0 || written == count)
+        if (written < 0 || !iov_iter_count(from))
                 return written;
 
         pos += written;
@@ -1720,13 +1719,14 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
         u64 end_pos;
         ssize_t num_written = 0;
         ssize_t err = 0;
-        size_t count, ocount;
+        size_t count;
         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
         struct iov_iter i;
 
         mutex_lock(&inode->i_mutex);
 
-        count = ocount = iov_length(iov, nr_segs);
+        count = iov_length(iov, nr_segs);
+        iov_iter_init(&i, WRITE, iov, nr_segs, count);
 
         current->backing_dev_info = inode->i_mapping->backing_dev_info;
         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
@@ -1740,7 +1740,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                 goto out;
         }
 
-        iov_iter_init(&i, WRITE, iov, nr_segs, count);
+        iov_iter_truncate(&i, count);
 
         err = file_remove_suid(file);
         if (err) {
@@ -1783,8 +1783,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                 atomic_inc(&BTRFS_I(inode)->sync_writers);
 
         if (unlikely(file->f_flags & O_DIRECT)) {
-                num_written = __btrfs_direct_write(iocb, &i,
-                                                   pos, count, ocount);
+                num_written = __btrfs_direct_write(iocb, &i, pos);
         } else {
                 num_written = __btrfs_buffered_write(file, &i, pos);
                 if (num_written > 0)