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Merge branch 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

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Pull nowait read support from Al Viro:
 "Support IOCB_NOWAIT for buffered reads and block devices"

* 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  block_dev: support RFW_NOWAIT on block device nodes
  fs: support RWF_NOWAIT for buffered reads
  fs: support IOCB_NOWAIT in generic_file_buffered_read
  fs: pass iocb to do_generic_file_read
This commit is contained in:
Linus Torvalds
2017-09-14 19:29:55 -07:00
parent 0f0d12728e c35fc7a5ab
commit e253d98f5b
7 changed files with 42 additions and 22 deletions
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24
mm/filemap.c
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@@ -1917,9 +1917,8 @@ static void shrink_readahead_size_eio(struct file *filp,
}
/**
* do_generic_file_read - generic file read routine
* @filp: the file to read
* @ppos: current file position
* generic_file_buffered_read - generic file read routine
* @iocb: the iocb to read
* @iter: data destination
* @written: already copied
*
@@ -1929,12 +1928,14 @@ static void shrink_readahead_size_eio(struct file *filp,
* This is really ugly. But the goto's actually try to clarify some
* of the logic when it comes to error handling etc.
*/
static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
static ssize_t generic_file_buffered_read(struct kiocb *iocb,
struct iov_iter *iter, ssize_t written)
{
struct file *filp = iocb->ki_filp;
struct address_space *mapping = filp->f_mapping;
struct inode *inode = mapping->host;
struct file_ra_state *ra = &filp->f_ra;
loff_t *ppos = &iocb->ki_pos;
pgoff_t index;
pgoff_t last_index;
pgoff_t prev_index;
@@ -1967,6 +1968,8 @@ find_page:
page = find_get_page(mapping, index);
if (!page) {
if (iocb->ki_flags & IOCB_NOWAIT)
goto would_block;
page_cache_sync_readahead(mapping,
ra, filp,
index, last_index - index);
@@ -1980,6 +1983,11 @@ find_page:
index, last_index - index);
}
if (!PageUptodate(page)) {
if (iocb->ki_flags & IOCB_NOWAIT) {
put_page(page);
goto would_block;
}
/*
* See comment in do_read_cache_page on why
* wait_on_page_locked is used to avoid unnecessarily
@@ -2161,6 +2169,8 @@ no_cached_page:
goto readpage;
}
would_block:
error = -EAGAIN;
out:
ra->prev_pos = prev_index;
ra->prev_pos <<= PAGE_SHIFT;
@@ -2182,14 +2192,14 @@ out:
ssize_t
generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
ssize_t retval = 0;
size_t count = iov_iter_count(iter);
ssize_t retval = 0;
if (!count)
goto out; /* skip atime */
if (iocb->ki_flags & IOCB_DIRECT) {
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
loff_t size;
@@ -2230,7 +2240,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
goto out;
}
retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval);
retval = generic_file_buffered_read(iocb, iter, retval);
out:
return retval;
}