mm: make read_cache_page synchronous

Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.

I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd.  All depending on whether the filler is async and/or can return
with a !uptodate page.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 8 insertions, 46 deletions

diff --git a/fs/ntfs/aops.h b/fs/ntfs/aops.h
index 9393f4b..caecc58 100644
--- a/fs/ntfs/aops.h
+++ b/fs/ntfs/aops.h
@@ -89,9 +89,8 @@ static inline struct page *ntfs_map_page(struct address_space *mapping,
 	struct page *page = read_mapping_page(mapping, index, NULL);
 
 	if (!IS_ERR(page)) {
-		wait_on_page_locked(page);
 		kmap(page);
-		if (PageUptodate(page) && !PageError(page))
+		if (!PageError(page))
 			return page;
 		ntfs_unmap_page(page);
 		return ERR_PTR(-EIO);
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 7659cc1..1c08fef 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -2532,14 +2532,7 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
 		page = read_mapping_page(mapping, idx, NULL);
 		if (IS_ERR(page)) {
 			ntfs_error(vol->sb, "Failed to read first partial "
-					"page (sync error, index 0x%lx).", idx);
-			return PTR_ERR(page);
-		}
-		wait_on_page_locked(page);
-		if (unlikely(!PageUptodate(page))) {
-			ntfs_error(vol->sb, "Failed to read first partial page "
-					"(async error, index 0x%lx).", idx);
-			page_cache_release(page);
+					"page (error, index 0x%lx).", idx);
 			return PTR_ERR(page);
 		}
 		/*
@@ -2602,14 +2595,7 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
 		page = read_mapping_page(mapping, idx, NULL);
 		if (IS_ERR(page)) {
 			ntfs_error(vol->sb, "Failed to read last partial page "
-					"(sync error, index 0x%lx).", idx);
-			return PTR_ERR(page);
-		}
-		wait_on_page_locked(page);
-		if (unlikely(!PageUptodate(page))) {
-			ntfs_error(vol->sb, "Failed to read last partial page "
-					"(async error, index 0x%lx).", idx);
-			page_cache_release(page);
+					"(error, index 0x%lx).", idx);
 			return PTR_ERR(page);
 		}
 		kaddr = kmap_atomic(page, KM_USER0);
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index d69c459..dbbac55 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -236,8 +236,7 @@ do_non_resident_extend:
 			err = PTR_ERR(page);
 			goto init_err_out;
 		}
-		wait_on_page_locked(page);
-		if (unlikely(!PageUptodate(page) || PageError(page))) {
+		if (unlikely(PageError(page))) {
 			page_cache_release(page);
 			err = -EIO;
 			goto init_err_out;
diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 1594c90..2ddde53 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -2471,7 +2471,6 @@ static s64 get_nr_free_clusters(ntfs_volume *vol)
 	s64 nr_free = vol->nr_clusters;
 	u32 *kaddr;
 	struct address_space *mapping = vol->lcnbmp_ino->i_mapping;
-	filler_t *readpage = (filler_t*)mapping->a_ops->readpage;
 	struct page *page;
 	pgoff_t index, max_index;
 
@@ -2494,24 +2493,14 @@ static s64 get_nr_free_clusters(ntfs_volume *vol)
 		 * Read the page from page cache, getting it from backing store
 		 * if necessary, and increment the use count.
 		 */
-		page = read_cache_page(mapping, index, (filler_t*)readpage,
-				NULL);
+		page = read_mapping_page(mapping, index, NULL);
 		/* Ignore pages which errored synchronously. */
 		if (IS_ERR(page)) {
-			ntfs_debug("Sync read_cache_page() error. Skipping "
+			ntfs_debug("read_mapping_page() error. Skipping "
 					"page (index 0x%lx).", index);
 			nr_free -= PAGE_CACHE_SIZE * 8;
 			continue;
 		}
-		wait_on_page_locked(page);
-		/* Ignore pages which errored asynchronously. */
-		if (!PageUptodate(page)) {
-			ntfs_debug("Async read_cache_page() error. Skipping "
-					"page (index 0x%lx).", index);
-			page_cache_release(page);
-			nr_free -= PAGE_CACHE_SIZE * 8;
-			continue;
-		}
 		kaddr = (u32*)kmap_atomic(page, KM_USER0);
 		/*
 		 * For each 4 bytes, subtract the number of set bits. If this
@@ -2562,7 +2551,6 @@ static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
 {
 	u32 *kaddr;
 	struct address_space *mapping = vol->mftbmp_ino->i_mapping;
-	filler_t *readpage = (filler_t*)mapping->a_ops->readpage;
 	struct page *page;
 	pgoff_t index;
 
@@ -2576,21 +2564,11 @@ static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
 		 * Read the page from page cache, getting it from backing store
 		 * if necessary, and increment the use count.
 		 */
-		page = read_cache_page(mapping, index, (filler_t*)readpage,
-				NULL);
+		page = read_mapping_page(mapping, index, NULL);
 		/* Ignore pages which errored synchronously. */
 		if (IS_ERR(page)) {
-			ntfs_debug("Sync read_cache_page() error. Skipping "
-					"page (index 0x%lx).", index);
-			nr_free -= PAGE_CACHE_SIZE * 8;
-			continue;
-		}
-		wait_on_page_locked(page);
-		/* Ignore pages which errored asynchronously. */
-		if (!PageUptodate(page)) {
-			ntfs_debug("Async read_cache_page() error. Skipping "
+			ntfs_debug("read_mapping_page() error. Skipping "
 					"page (index 0x%lx).", index);
-			page_cache_release(page);
 			nr_free -= PAGE_CACHE_SIZE * 8;
 			continue;
 		}