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fs: add vfs_iter_{read,write} helpers

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Simple helpers that pass an arbitrary iov_iter to filesystems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2015-01-25 21:11:59 +01:00 committed by Al Viro
parent 05afcb77eb
commit dbe4e192a2
3 changed files with 51 additions and 14 deletions
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46
fs/read_write.c
View File

@ -333,6 +333,52 @@ out_putf:
}
#endif
ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos)
{
struct kiocb kiocb;
ssize_t ret;
if (!file->f_op->read_iter)
return -EINVAL;
init_sync_kiocb(&kiocb, file);
kiocb.ki_pos = *ppos;
kiocb.ki_nbytes = iov_iter_count(iter);
iter->type |= READ;
ret = file->f_op->read_iter(&kiocb, iter);
if (ret == -EIOCBQUEUED)
ret = wait_on_sync_kiocb(&kiocb);
if (ret > 0)
*ppos = kiocb.ki_pos;
return ret;
}
EXPORT_SYMBOL(vfs_iter_read);
ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos)
{
struct kiocb kiocb;
ssize_t ret;
if (!file->f_op->write_iter)
return -EINVAL;
init_sync_kiocb(&kiocb, file);
kiocb.ki_pos = *ppos;
kiocb.ki_nbytes = iov_iter_count(iter);
iter->type |= WRITE;
ret = file->f_op->write_iter(&kiocb, iter);
if (ret == -EIOCBQUEUED)
ret = wait_on_sync_kiocb(&kiocb);
if (ret > 0)
*ppos = kiocb.ki_pos;
return ret;
}
EXPORT_SYMBOL(vfs_iter_write);
/*
* rw_verify_area doesn't like huge counts. We limit
* them to something that fits in "int" so that others

16
fs/splice.c
View File

@ -961,7 +961,6 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
splice_from_pipe_begin(&sd);
while (sd.total_len) {
struct iov_iter from;
struct kiocb kiocb;
size_t left;
int n, idx;
@ -1005,26 +1004,15 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
left -= this_len;
}
/* ... iov_iter */
iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
sd.total_len - left);
/* ... and iocb */
init_sync_kiocb(&kiocb, out);
kiocb.ki_pos = sd.pos;
kiocb.ki_nbytes = sd.total_len - left;
/* now, send it */
ret = out->f_op->write_iter(&kiocb, &from);
if (-EIOCBQUEUED == ret)
ret = wait_on_sync_kiocb(&kiocb);
ret = vfs_iter_write(out, &from, &sd.pos);
if (ret <= 0)
break;
sd.num_spliced += ret;
sd.total_len -= ret;
*ppos = sd.pos = kiocb.ki_pos;
*ppos = sd.pos;
/* dismiss the fully eaten buffers, adjust the partial one */
while (ret) {

3
include/linux/fs.h
View File

@ -2494,6 +2494,9 @@ extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t l
extern ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos);
ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos);
/* fs/block_dev.c */
extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);