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>

1 files changed, 4 insertions, 26 deletions

diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 1594c90b7164..2ddde534db0a 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;
                 }