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authorMiklos Szeredi <mszeredi@suse.cz>2008-08-01 20:28:47 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2008-08-02 09:12:34 -0700
commit84209e02de48d72289650cc5a7ae8dd18223620f (patch)
treea02ffe41273c4371262409a51d07461a674cea66 /mm/truncate.c
parent2b12a4c524812fb3f6ee590a02e65b95c8c32229 (diff)
downloadvexpress-lsk-84209e02de48d72289650cc5a7ae8dd18223620f.tar.gz
mm: dont clear PG_uptodate on truncate/invalidate
Brian Wang reported that a FUSE filesystem exported through NFS could return I/O errors on read. This was traced to splice_direct_to_actor() returning a short or zero count when racing with page invalidation. However this is not FUSE or NFSD specific, other filesystems (notably NFS) also call invalidate_inode_pages2() to purge stale data from the cache. If this happens while such pages are sitting in a pipe buffer, then splice(2) from the pipe can return zero, and read(2) from the pipe can return ENODATA. The zero return is especially bad, since it implies end-of-file or disconnected pipe/socket, and is documented as such for splice. But returning an error for read() is also nasty, when in fact there was no error (data becoming stale is not an error). The same problems can be triggered by "hole punching" with madvise(MADV_REMOVE). Fix this by not clearing the PG_uptodate flag on truncation and invalidation. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/truncate.c')
-rw-r--r--mm/truncate.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index e68443d7456..894e9a70699 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -104,7 +104,6 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
cancel_dirty_page(page, PAGE_CACHE_SIZE);
remove_from_page_cache(page);
- ClearPageUptodate(page);
ClearPageMappedToDisk(page);
page_cache_release(page); /* pagecache ref */
}
@@ -356,7 +355,6 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
BUG_ON(PagePrivate(page));
__remove_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
- ClearPageUptodate(page);
page_cache_release(page); /* pagecache ref */
return 1;
failed: