Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6fe6900e1e5b6fa9e5c59aa5061f244fe3f467e2
Commit:     6fe6900e1e5b6fa9e5c59aa5061f244fe3f467e2
Parent:     714b8171af9c930a59a0da8f6fe50518e70ab035
Author:     Nick Piggin <[EMAIL PROTECTED]>
AuthorDate: Sun May 6 14:49:04 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon May 7 12:12:51 2007 -0700

    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 <[EMAIL PROTECTED]>
    Cc: Hugh Dickins <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 drivers/mtd/devices/block2mtd.c |    6 +---
 fs/afs/dir.c                    |    3 --
 fs/afs/mntpt.c                  |   11 +++-----
 fs/cramfs/inode.c               |    3 +-
 fs/ecryptfs/mmap.c              |   11 +--------
 fs/ext2/dir.c                   |    3 --
 fs/freevxfs/vxfs_subr.c         |    3 --
 fs/minix/dir.c                  |    1 -
 fs/namei.c                      |   12 +--------
 fs/nfs/dir.c                    |    5 ----
 fs/nfs/symlink.c                |    6 ----
 fs/ntfs/aops.h                  |    3 +-
 fs/ntfs/attrib.c                |   18 +------------
 fs/ntfs/file.c                  |    3 +-
 fs/ntfs/super.c                 |   30 +++--------------------
 fs/ocfs2/symlink.c              |    7 -----
 fs/partitions/check.c           |    3 --
 fs/reiserfs/xattr.c             |    4 ---
 fs/sysv/dir.c                   |   10 +-------
 fs/ufs/dir.c                    |    6 +----
 fs/ufs/util.c                   |    6 +---
 include/linux/pagemap.h         |   11 ++++++++
 mm/filemap.c                    |   49 ++++++++++++++++++++++++++++++--------
 mm/swapfile.c                   |    3 --
 24 files changed, 71 insertions(+), 146 deletions(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index ce47544..fc4cc8b 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -40,13 +40,11 @@ struct block2mtd_dev {
 static LIST_HEAD(blkmtd_device_list);
 
 
-static struct page* page_read(struct address_space *mapping, int index)
+static struct page *page_read(struct address_space *mapping, int index)
 {
-       filler_t *filler = (filler_t*)mapping->a_ops->readpage;
-       return read_cache_page(mapping, index, filler, NULL);
+       return read_mapping_page(mapping, index, NULL);
 }
 
-
 /* erase a specified part of the device */
 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
 {
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index dac5b99..0c1e902 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -194,10 +194,7 @@ static struct page *afs_dir_get_page(struct inode *dir, 
unsigned long index,
 
        page = read_mapping_page(dir->i_mapping, index, &file);
        if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
                kmap(page);
-               if (!PageUptodate(page))
-                       goto fail;
                if (!PageChecked(page))
                        afs_dir_check_page(dir, page);
                if (PageError(page))
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index b905ae3..034fcfd 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -68,13 +68,11 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct 
key *key)
        }
 
        ret = -EIO;
-       wait_on_page_locked(page);
-       buf = kmap(page);
-       if (!PageUptodate(page))
-               goto out_free;
        if (PageError(page))
                goto out_free;
 
+       buf = kmap(page);
+
        /* examine the symlink's contents */
        size = vnode->status.size;
        _debug("symlink to %*.*s", (int) size, (int) size, buf);
@@ -91,8 +89,8 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct 
key *key)
 
        ret = 0;
 
-out_free:
        kunmap(page);
+out_free:
        page_cache_release(page);
 out:
        _leave(" = %d", ret);
@@ -171,8 +169,7 @@ static struct vfsmount *afs_mntpt_do_automount(struct 
dentry *mntpt)
        }
 
        ret = -EIO;
-       wait_on_page_locked(page);
-       if (!PageUptodate(page) || PageError(page))
+       if (PageError(page))
                goto error;
 
        buf = kmap(page);
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index facd0c8..3d194a2 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -180,7 +180,8 @@ static void *cramfs_read(struct super_block *sb, unsigned 
int offset, unsigned i
                struct page *page = NULL;
 
                if (blocknr + i < devsize) {
-                       page = read_mapping_page(mapping, blocknr + i, NULL);
+                       page = read_mapping_page_async(mapping, blocknr + i,
+                                                                       NULL);
                        /* synchronous error? */
                        if (IS_ERR(page))
                                page = NULL;
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index b731b09..0770c4b 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -46,7 +46,6 @@ struct kmem_cache *ecryptfs_lower_page_cache;
  */
 static struct page *ecryptfs_get1page(struct file *file, int index)
 {
-       struct page *page;
        struct dentry *dentry;
        struct inode *inode;
        struct address_space *mapping;
@@ -54,14 +53,7 @@ static struct page *ecryptfs_get1page(struct file *file, int 
index)
        dentry = file->f_path.dentry;
        inode = dentry->d_inode;
        mapping = inode->i_mapping;
-       page = read_cache_page(mapping, index,
-                              (filler_t *)mapping->a_ops->readpage,
-                              (void *)file);
-       if (IS_ERR(page))
-               goto out;
-       wait_on_page_locked(page);
-out:
-       return page;
+       return read_mapping_page(mapping, index, (void *)file);
 }
 
 static
@@ -233,7 +225,6 @@ int ecryptfs_do_readpage(struct file *file, struct page 
*page,
                ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
                goto out;
        }
-       wait_on_page_locked(lower_page);
        page_data = kmap_atomic(page, KM_USER0);
        lower_page_data = kmap_atomic(lower_page, KM_USER1);
        memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index e89bfc8..1d1e7e3 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -161,10 +161,7 @@ static struct page * ext2_get_page(struct inode *dir, 
unsigned long n)
        struct address_space *mapping = dir->i_mapping;
        struct page *page = read_mapping_page(mapping, n, NULL);
        if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
                kmap(page);
-               if (!PageUptodate(page))
-                       goto fail;
                if (!PageChecked(page))
                        ext2_check_page(page);
                if (PageError(page))
diff --git a/fs/freevxfs/vxfs_subr.c b/fs/freevxfs/vxfs_subr.c
index decac62..ed8f0b0 100644
--- a/fs/freevxfs/vxfs_subr.c
+++ b/fs/freevxfs/vxfs_subr.c
@@ -74,10 +74,7 @@ vxfs_get_page(struct address_space *mapping, u_long n)
        pp = read_mapping_page(mapping, n, NULL);
 
        if (!IS_ERR(pp)) {
-               wait_on_page_locked(pp);
                kmap(pp);
-               if (!PageUptodate(pp))
-                       goto fail;
                /** if (!PageChecked(pp)) **/
                        /** vxfs_check_page(pp); **/
                if (PageError(pp))
diff --git a/fs/minix/dir.c b/fs/minix/dir.c
index cb4cb57..e207cbe 100644
--- a/fs/minix/dir.c
+++ b/fs/minix/dir.c
@@ -65,7 +65,6 @@ static struct page * dir_get_page(struct inode *dir, unsigned 
long n)
        struct address_space *mapping = dir->i_mapping;
        struct page *page = read_mapping_page(mapping, n, NULL);
        if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
                kmap(page);
                if (!PageUptodate(page))
                        goto fail;
diff --git a/fs/namei.c b/fs/namei.c
index 880052c..94b2f60 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2671,19 +2671,9 @@ static char *page_getlink(struct dentry * dentry, struct 
page **ppage)
        struct address_space *mapping = dentry->d_inode->i_mapping;
        page = read_mapping_page(mapping, 0, NULL);
        if (IS_ERR(page))
-               goto sync_fail;
-       wait_on_page_locked(page);
-       if (!PageUptodate(page))
-               goto async_fail;
+               return (char*)page;
        *ppage = page;
        return kmap(page);
-
-async_fail:
-       page_cache_release(page);
-       return ERR_PTR(-EIO);
-
-sync_fail:
-       return (char*)page;
 }
 
 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index e59fd31..625d8e5 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -334,8 +334,6 @@ int find_dirent_page(nfs_readdir_descriptor_t *desc)
                status = PTR_ERR(page);
                goto out;
        }
-       if (!PageUptodate(page))
-               goto read_error;
 
        /* NOTE: Someone else may have changed the READDIRPLUS flag */
        desc->page = page;
@@ -349,9 +347,6 @@ int find_dirent_page(nfs_readdir_descriptor_t *desc)
  out:
        dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __FUNCTION__, status);
        return status;
- read_error:
-       page_cache_release(page);
-       return -EIO;
 }
 
 /*
diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
index f4a0548..bc28213 100644
--- a/fs/nfs/symlink.c
+++ b/fs/nfs/symlink.c
@@ -61,15 +61,9 @@ static void *nfs_follow_link(struct dentry *dentry, struct 
nameidata *nd)
                err = page;
                goto read_failed;
        }
-       if (!PageUptodate(page)) {
-               err = ERR_PTR(-EIO);
-               goto getlink_read_error;
-       }
        nd_set_link(nd, kmap(page));
        return page;
 
-getlink_read_error:
-       page_cache_release(page);
 read_failed:
        nd_set_link(nd, err);
        return NULL;
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;
                }
diff --git a/fs/ocfs2/symlink.c b/fs/ocfs2/symlink.c
index 40dc1a5..7134007 100644
--- a/fs/ocfs2/symlink.c
+++ b/fs/ocfs2/symlink.c
@@ -67,16 +67,9 @@ static char *ocfs2_page_getlink(struct dentry * dentry,
        page = read_mapping_page(mapping, 0, NULL);
        if (IS_ERR(page))
                goto sync_fail;
-       wait_on_page_locked(page);
-       if (!PageUptodate(page))
-               goto async_fail;
        *ppage = page;
        return kmap(page);
 
-async_fail:
-       page_cache_release(page);
-       return ERR_PTR(-EIO);
-
 sync_fail:
        return (char*)page;
 }
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index f01572f..6b9dae3 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -569,9 +569,6 @@ unsigned char *read_dev_sector(struct block_device *bdev, 
sector_t n, Sector *p)
        page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
                                 NULL);
        if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
-               if (!PageUptodate(page))
-                       goto fail;
                if (PageError(page))
                        goto fail;
                p->v = page;
diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 2cac562..bf6e582 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -410,11 +410,7 @@ static struct page *reiserfs_get_page(struct inode *dir, 
unsigned long n)
        mapping_set_gfp_mask(mapping, GFP_NOFS);
        page = read_mapping_page(mapping, n, NULL);
        if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
                kmap(page);
-               if (!PageUptodate(page))
-                       goto fail;
-
                if (PageError(page))
                        goto fail;
        }
diff --git a/fs/sysv/dir.c b/fs/sysv/dir.c
index ebf7007..e566b38 100644
--- a/fs/sysv/dir.c
+++ b/fs/sysv/dir.c
@@ -54,17 +54,9 @@ static struct page * dir_get_page(struct inode *dir, 
unsigned long n)
 {
        struct address_space *mapping = dir->i_mapping;
        struct page *page = read_mapping_page(mapping, n, NULL);
-       if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
+       if (!IS_ERR(page))
                kmap(page);
-               if (!PageUptodate(page))
-                       goto fail;
-       }
        return page;
-
-fail:
-       dir_put_page(page);
-       return ERR_PTR(-EIO);
 }
 
 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
diff --git a/fs/ufs/dir.c b/fs/ufs/dir.c
index 4890ddf..4fb8b2e 100644
--- a/fs/ufs/dir.c
+++ b/fs/ufs/dir.c
@@ -180,13 +180,9 @@ fail:
 static struct page *ufs_get_page(struct inode *dir, unsigned long n)
 {
        struct address_space *mapping = dir->i_mapping;
-       struct page *page = read_cache_page(mapping, n,
-                               (filler_t*)mapping->a_ops->readpage, NULL);
+       struct page *page = read_mapping_page(mapping, n, NULL);
        if (!IS_ERR(page)) {
-               wait_on_page_locked(page);
                kmap(page);
-               if (!PageUptodate(page))
-                       goto fail;
                if (!PageChecked(page))
                        ufs_check_page(page);
                if (PageError(page))
diff --git a/fs/ufs/util.c b/fs/ufs/util.c
index 1743757..84357f1 100644
--- a/fs/ufs/util.c
+++ b/fs/ufs/util.c
@@ -251,13 +251,11 @@ struct page *ufs_get_locked_page(struct address_space 
*mapping,
 
        page = find_lock_page(mapping, index);
        if (!page) {
-               page = read_cache_page(mapping, index,
-                                      (filler_t*)mapping->a_ops->readpage,
-                                      NULL);
+               page = read_mapping_page(mapping, index, NULL);
 
                if (IS_ERR(page)) {
                        printk(KERN_ERR "ufs_change_blocknr: "
-                              "read_cache_page error: ino %lu, index: %lu\n",
+                              "read_mapping_page error: ino %lu, index: %lu\n",
                               mapping->host->i_ino, index);
                        goto out;
                }
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 7a8dcb8..b4def5e 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -95,12 +95,23 @@ static inline struct page *grab_cache_page(struct 
address_space *mapping, unsign
 
 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
                                unsigned long index);
+extern struct page * read_cache_page_async(struct address_space *mapping,
+                               unsigned long index, filler_t *filler,
+                               void *data);
 extern struct page * read_cache_page(struct address_space *mapping,
                                unsigned long index, filler_t *filler,
                                void *data);
 extern int read_cache_pages(struct address_space *mapping,
                struct list_head *pages, filler_t *filler, void *data);
 
+static inline struct page *read_mapping_page_async(
+                                               struct address_space *mapping,
+                                            unsigned long index, void *data)
+{
+       filler_t *filler = (filler_t *)mapping->a_ops->readpage;
+       return read_cache_page_async(mapping, index, filler, data);
+}
+
 static inline struct page *read_mapping_page(struct address_space *mapping,
                                             unsigned long index, void *data)
 {
diff --git a/mm/filemap.c b/mm/filemap.c
index 5dfc093..070e754 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1726,7 +1726,7 @@ int generic_file_readonly_mmap(struct file * file, struct 
vm_area_struct * vma)
 EXPORT_SYMBOL(generic_file_mmap);
 EXPORT_SYMBOL(generic_file_readonly_mmap);
 
-static inline struct page *__read_cache_page(struct address_space *mapping,
+static struct page *__read_cache_page(struct address_space *mapping,
                                unsigned long index,
                                int (*filler)(void *,struct page*),
                                void *data)
@@ -1763,17 +1763,11 @@ repeat:
        return page;
 }
 
-/**
- * read_cache_page - read into page cache, fill it if needed
- * @mapping:   the page's address_space
- * @index:     the page index
- * @filler:    function to perform the read
- * @data:      destination for read data
- *
- * Read into the page cache. If a page already exists,
- * and PageUptodate() is not set, try to fill the page.
+/*
+ * Same as read_cache_page, but don't wait for page to become unlocked
+ * after submitting it to the filler.
  */
-struct page *read_cache_page(struct address_space *mapping,
+struct page *read_cache_page_async(struct address_space *mapping,
                                unsigned long index,
                                int (*filler)(void *,struct page*),
                                void *data)
@@ -1805,6 +1799,39 @@ retry:
                page = ERR_PTR(err);
        }
  out:
+       mark_page_accessed(page);
+       return page;
+}
+EXPORT_SYMBOL(read_cache_page_async);
+
+/**
+ * read_cache_page - read into page cache, fill it if needed
+ * @mapping:   the page's address_space
+ * @index:     the page index
+ * @filler:    function to perform the read
+ * @data:      destination for read data
+ *
+ * Read into the page cache. If a page already exists, and PageUptodate() is
+ * not set, try to fill the page then wait for it to become unlocked.
+ *
+ * If the page does not get brought uptodate, return -EIO.
+ */
+struct page *read_cache_page(struct address_space *mapping,
+                               unsigned long index,
+                               int (*filler)(void *,struct page*),
+                               void *data)
+{
+       struct page *page;
+
+       page = read_cache_page_async(mapping, index, filler, data);
+       if (IS_ERR(page))
+               goto out;
+       wait_on_page_locked(page);
+       if (!PageUptodate(page)) {
+               page_cache_release(page);
+               page = ERR_PTR(-EIO);
+       }
+ out:
        return page;
 }
 EXPORT_SYMBOL(read_cache_page);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index a2d9bb4..acc172c 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1531,9 +1531,6 @@ asmlinkage long sys_swapon(const char __user * 
specialfile, int swap_flags)
                error = PTR_ERR(page);
                goto bad_swap;
        }
-       wait_on_page_locked(page);
-       if (!PageUptodate(page))
-               goto bad_swap;
        kmap(page);
        swap_header = page_address(page);
 
-
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