[patch 3/3] mm: make read_cache_page synchronous

From: Nick Piggin
Date: Thu Feb 08 2007 - 08:28:26 EST

Next message: Andi Kleen: "Re: [PATCH 9/11] Panic delay fix"
Previous message: Nick Piggin: "[patch 2/3] fs: buffer don't PageUptodate without page locked"
In reply to: Nick Piggin: "[patch 2/3] fs: buffer don't PageUptodate without page locked"
Next in thread: Benjamin Herrenschmidt: "Re: [patch 0/3] 2.6.20 fix for PageUptodate memorder problem (try2)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate_NoLock 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@xxxxxxx>

drivers/mtd/devices/block2mtd.c | 3 --
fs/afs/dir.c | 3 --
fs/afs/mntpt.c | 11 +++------
fs/cramfs/inode.c | 3 +-
fs/ecryptfs/mmap.c | 10 --------
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 | 48 ++++++++++++++++++++++++++++++----------
mm/swapfile.c | 3 --
24 files changed, 68 insertions(+), 144 deletions(-)

Index: linux-2.6/fs/afs/dir.c
===================================================================
--- linux-2.6.orig/fs/afs/dir.c
+++ linux-2.6/fs/afs/dir.c
@@ -187,10 +187,7 @@ static struct page *afs_dir_get_page(str

page = read_mapping_page(dir->i_mapping, index, NULL);
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))
Index: linux-2.6/fs/afs/mntpt.c
===================================================================
--- linux-2.6.orig/fs/afs/mntpt.c
+++ linux-2.6/fs/afs/mntpt.c
@@ -77,13 +77,11 @@ int afs_mntpt_check_symlink(struct afs_v
}

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", size, (int) size, buf);
@@ -100,8 +98,8 @@ int afs_mntpt_check_symlink(struct afs_v

ret = 0;

- out_free:
kunmap(page);
+ out_free:
page_cache_release(page);
out:
_leave(" = %d", ret);
@@ -184,8 +182,7 @@ static struct vfsmount *afs_mntpt_do_aut
}

ret = -EIO;
- wait_on_page_locked(page);
- if (!PageUptodate(page) || PageError(page))
+ if (PageError(page))
goto error;

buf = kmap(page);
Index: linux-2.6/fs/cramfs/inode.c
===================================================================
--- linux-2.6.orig/fs/cramfs/inode.c
+++ linux-2.6/fs/cramfs/inode.c
@@ -180,7 +180,8 @@ static void *cramfs_read(struct super_bl
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;
Index: linux-2.6/fs/ext2/dir.c
===================================================================
--- linux-2.6.orig/fs/ext2/dir.c
+++ linux-2.6/fs/ext2/dir.c
@@ -161,10 +161,7 @@ static struct page * ext2_get_page(struc
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_NoLock(page))
- goto fail;
if (!PageChecked(page))
ext2_check_page(page);
if (PageError(page))
Index: linux-2.6/fs/freevxfs/vxfs_subr.c
===================================================================
--- linux-2.6.orig/fs/freevxfs/vxfs_subr.c
+++ linux-2.6/fs/freevxfs/vxfs_subr.c
@@ -74,10 +74,7 @@ vxfs_get_page(struct address_space *mapp
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))
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -1756,7 +1756,7 @@ int generic_file_readonly_mmap(struct fi
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)
@@ -1793,17 +1793,11 @@ 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)
@@ -1815,7 +1809,6 @@ retry:
page = __read_cache_page(mapping, index, filler, data);
if (IS_ERR(page))
goto out;
- mark_page_accessed(page);
if (PageUptodate_NoLock(page))
goto out;

@@ -1835,6 +1828,37 @@ 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.
+ */
+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_NoLock(page)) {
+ page_cache_release(page);
+ page = ERR_PTR(-EIO);
+ }
+ out:
return page;
}
EXPORT_SYMBOL(read_cache_page);
Index: linux-2.6/fs/minix/dir.c
===================================================================
--- linux-2.6.orig/fs/minix/dir.c
+++ linux-2.6/fs/minix/dir.c
@@ -62,7 +62,6 @@ static struct page * dir_get_page(struct
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;
Index: linux-2.6/fs/namei.c
===================================================================
--- linux-2.6.orig/fs/namei.c
+++ linux-2.6/fs/namei.c
@@ -2639,19 +2639,9 @@ static char *page_getlink(struct dentry
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_NoLock(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)
Index: linux-2.6/fs/ntfs/aops.h
===================================================================
--- linux-2.6.orig/fs/ntfs/aops.h
+++ linux-2.6/fs/ntfs/aops.h
@@ -89,9 +89,8 @@ static inline struct page *ntfs_map_page
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);
Index: linux-2.6/fs/ntfs/attrib.c
===================================================================
--- linux-2.6.orig/fs/ntfs/attrib.c
+++ linux-2.6/fs/ntfs/attrib.c
@@ -2532,14 +2532,7 @@ int ntfs_attr_set(ntfs_inode *ni, const
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
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);
Index: linux-2.6/fs/ntfs/file.c
===================================================================
--- linux-2.6.orig/fs/ntfs/file.c
+++ linux-2.6/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;
Index: linux-2.6/fs/ocfs2/symlink.c
===================================================================
--- linux-2.6.orig/fs/ocfs2/symlink.c
+++ linux-2.6/fs/ocfs2/symlink.c
@@ -67,16 +67,9 @@ static char *ocfs2_page_getlink(struct d
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;
}
Index: linux-2.6/fs/partitions/check.c
===================================================================
--- linux-2.6.orig/fs/partitions/check.c
+++ linux-2.6/fs/partitions/check.c
@@ -561,9 +561,6 @@ unsigned char *read_dev_sector(struct bl
page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
NULL);
if (!IS_ERR(page)) {
- wait_on_page_locked(page);
- if (!PageUptodate_NoLock(page))
- goto fail;
if (PageError(page))
goto fail;
p->v = page;
Index: linux-2.6/fs/reiserfs/xattr.c
===================================================================
--- linux-2.6.orig/fs/reiserfs/xattr.c
+++ linux-2.6/fs/reiserfs/xattr.c
@@ -454,11 +454,7 @@ static struct page *reiserfs_get_page(st
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;
}
Index: linux-2.6/fs/sysv/dir.c
===================================================================
--- linux-2.6.orig/fs/sysv/dir.c
+++ linux-2.6/fs/sysv/dir.c
@@ -54,17 +54,9 @@ static struct page * dir_get_page(struct
{
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)
Index: linux-2.6/mm/swapfile.c
===================================================================
--- linux-2.6.orig/mm/swapfile.c
+++ linux-2.6/mm/swapfile.c
@@ -1531,9 +1531,6 @@ asmlinkage long sys_swapon(const char __
error = PTR_ERR(page);
goto bad_swap;
}
- wait_on_page_locked(page);
- if (!PageUptodate_NoLock(page))
- goto bad_swap;
kmap(page);
swap_header = page_address(page);

Index: linux-2.6/drivers/mtd/devices/block2mtd.c
===================================================================
--- linux-2.6.orig/drivers/mtd/devices/block2mtd.c
+++ linux-2.6/drivers/mtd/devices/block2mtd.c
@@ -88,9 +88,8 @@ static void cache_readahead(struct addre

static struct page* page_readahead(struct address_space *mapping, int index)
{
- filler_t *filler = (filler_t*)mapping->a_ops->readpage;
cache_readahead(mapping, index);
- return read_cache_page(mapping, index, filler, NULL);
+ return read_mapping_page(mapping, index, NULL);
}

Index: linux-2.6/fs/ecryptfs/mmap.c
===================================================================
--- linux-2.6.orig/fs/ecryptfs/mmap.c
+++ linux-2.6/fs/ecryptfs/mmap.c
@@ -54,14 +54,7 @@ static struct page *ecryptfs_get1page(st
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 +226,6 @@ int ecryptfs_do_readpage(struct file *fi
ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
goto out;
}
- wait_on_page_locked(lower_page);
page_data = (char *)kmap(page);
if (!page_data) {
rc = -ENOMEM;
Index: linux-2.6/fs/nfs/dir.c
===================================================================
--- linux-2.6.orig/fs/nfs/dir.c
+++ linux-2.6/fs/nfs/dir.c
@@ -322,8 +322,6 @@ int find_dirent_page(nfs_readdir_descrip
status = PTR_ERR(page);
goto out;
}
- if (!PageUptodate(page))
- goto read_error;

/* NOTE: Someone else may have changed the READDIRPLUS flag */
desc->page = page;
@@ -337,9 +335,6 @@ int find_dirent_page(nfs_readdir_descrip
out:
dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __FUNCTION__, status);
return status;
- read_error:
- page_cache_release(page);
- return -EIO;
}

/*
Index: linux-2.6/fs/nfs/symlink.c
===================================================================
--- linux-2.6.orig/fs/nfs/symlink.c
+++ linux-2.6/fs/nfs/symlink.c
@@ -61,15 +61,9 @@ static void *nfs_follow_link(struct dent
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;
Index: linux-2.6/fs/ntfs/super.c
===================================================================
--- linux-2.6.orig/fs/ntfs/super.c
+++ linux-2.6/fs/ntfs/super.c
@@ -2471,7 +2471,6 @@ static s64 get_nr_free_clusters(ntfs_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_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_r
{
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_r
* 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;
}
Index: linux-2.6/fs/ufs/dir.c
===================================================================
--- linux-2.6.orig/fs/ufs/dir.c
+++ linux-2.6/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))
Index: linux-2.6/fs/ufs/util.c
===================================================================
--- linux-2.6.orig/fs/ufs/util.c
+++ linux-2.6/fs/ufs/util.c
@@ -251,13 +251,11 @@ struct page *ufs_get_locked_page(struct

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;
}
Index: linux-2.6/include/linux/pagemap.h
===================================================================
--- linux-2.6.orig/include/linux/pagemap.h
+++ linux-2.6/include/linux/pagemap.h
@@ -97,12 +97,23 @@ static inline struct page *grab_cache_pa

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)
{
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Andi Kleen: "Re: [PATCH 9/11] Panic delay fix"
Previous message: Nick Piggin: "[patch 2/3] fs: buffer don't PageUptodate without page locked"
In reply to: Nick Piggin: "[patch 2/3] fs: buffer don't PageUptodate without page locked"
Next in thread: Benjamin Herrenschmidt: "Re: [patch 0/3] 2.6.20 fix for PageUptodate memorder problem (try2)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]