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authorMilosz Tanski <milosz@adfin.com>2017-08-29 16:13:19 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2017-09-04 19:04:22 -0400
commit3239d834847627b6634a4139cf1dc58f6f137a46 (patch)
tree7fb8e4424d69ecd3cc0d4d151464f513942d7bfb /mm/filemap.c
parent47c27bc46946dea543196a92061da14c6da9889e (diff)
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fs: support IOCB_NOWAIT in generic_file_buffered_read
Allow generic_file_buffered_read to bail out early instead of waiting for the page lock or reading a page if IOCB_NOWAIT is specified. Signed-off-by: Milosz Tanski <milosz@adfin.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Sage Weil <sage@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index b7c039669020..92d4e0a6c012 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1939,6 +1939,8 @@ 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);
@@ -1952,6 +1954,11 @@ 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
@@ -2133,6 +2140,8 @@ no_cached_page:
goto readpage;
}
+would_block:
+ error = -EAGAIN;
out:
ra->prev_pos = prev_index;
ra->prev_pos <<= PAGE_SHIFT;