btrfs: add support for read_iter and write_iter

btrfs can use generic_file_read_iter(). Base btrfs_file_write_iter()
on btrfs_file_aio_write(), then have the latter call the former.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Zach Brown <zab@zabbo.net>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: linux-btrfs@vger.kernel.org

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 72da4df53c9a224d7a5106a907fc4ba4e08f5ebb..5e70fc2cef27f886a8dbe65dedc13a5cba0cf094 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -453,7 +453,7 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
                write_bytes -= copied;
                total_copied += copied;
 
-               /* Return to btrfs_file_aio_write to fault page */
+               /* Return to btrfs_file_write_iter to fault page */
                if (unlikely(copied == 0))
                        break;
 
@@ -1557,27 +1557,23 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 }
 
 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
-                                   const struct iovec *iov,
-                                   unsigned long nr_segs, loff_t pos,
-                                   loff_t *ppos, size_t count, size_t ocount)
+                                    struct iov_iter *iter, loff_t pos,
+                                   loff_t *ppos, size_t count)
 {
        struct file *file = iocb->ki_filp;
-       struct iov_iter i;
        ssize_t written;
        ssize_t written_buffered;
        loff_t endbyte;
        int err;
 
-       written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
-                                           count, ocount);
+       written = generic_file_direct_write_iter(iocb, iter, pos, ppos, count);
 
        if (written < 0 || written == count)
                return written;
 
        pos += written;
        count -= written;
-       iov_iter_init(&i, iov, nr_segs, count, written);
-       written_buffered = __btrfs_buffered_write(file, &i, pos);
+       written_buffered = __btrfs_buffered_write(file, iter, pos);
        if (written_buffered < 0) {
                err = written_buffered;
                goto out;
@@ -1612,9 +1608,8 @@ static void update_time_for_write(struct inode *inode)
                inode_inc_iversion(inode);
 }
 
-static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
-                                   const struct iovec *iov,
-                                   unsigned long nr_segs, loff_t pos)
+static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
+                                    struct iov_iter *iter, loff_t pos)
 {
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
@@ -1623,17 +1618,12 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
        u64 start_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);
 
        mutex_lock(&inode->i_mutex);
 
-       err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
-       if (err) {
-               mutex_unlock(&inode->i_mutex);
-               goto out;
-       }
-       count = ocount;
+       count = iov_iter_count(iter);
 
        current->backing_dev_info = inode->i_mapping->backing_dev_info;
        err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
@@ -1686,14 +1676,10 @@ 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, iov, nr_segs,
-                                                  pos, ppos, count, ocount);
+               num_written = __btrfs_direct_write(iocb, iter, pos, ppos,
+                                                  count);
        } else {
-               struct iov_iter i;
-
-               iov_iter_init(&i, iov, nr_segs, count, num_written);
-
-               num_written = __btrfs_buffered_write(file, &i, pos);
+               num_written = __btrfs_buffered_write(file, iter, pos);
                if (num_written > 0)
                        *ppos = pos + num_written;
        }
@@ -2552,9 +2538,9 @@ const struct file_operations btrfs_file_operations = {
        .llseek         = btrfs_file_llseek,
        .read           = do_sync_read,
        .write          = do_sync_write,
-       .aio_read       = generic_file_aio_read,
        .splice_read    = generic_file_splice_read,
-       .aio_write      = btrfs_file_aio_write,
+       .read_iter      = generic_file_read_iter,
+       .write_iter     = btrfs_file_write_iter,
        .mmap           = btrfs_file_mmap,
        .open           = generic_file_open,
        .release        = btrfs_release_file,