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authorLinus Torvalds <torvalds@linux-foundation.org>2017-09-14 19:29:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-14 19:29:55 -0700
commite253d98f5babbec7e6ced810f7335b265a7f7e83 (patch)
treecd688c4ba8d43edb12bbeb523393879f7c212b65 /mm
parent0f0d12728e56c94d3289c6831243b6faeae8a19d (diff)
parentc35fc7a5abae9c154dd6f8c0b288462342facd45 (diff)
download96b-common-e253d98f5babbec7e6ced810f7335b265a7f7e83.tar.gz
Merge branch 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
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
Diffstat (limited to 'mm')
-rw-r--r--mm/filemap.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 8c88e186a773..870971e20967 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -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;
}