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Subject[patch 09/28] mm: page_mkwrite change prototype to match fault
2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Nick Piggin <npiggin@suse.de>

commit c2ec175c39f62949438354f603f4aa170846aabb upstream


mm: page_mkwrite change prototype to match fault

Change the page_mkwrite prototype to take a struct vm_fault, and return
VM_FAULT_xxx flags. There should be no functional change.

This makes it possible to return much more detailed error information to
the VM (and also can provide more information eg. virtual_address to the
driver, which might be important in some special cases).

This is required for a subsequent fix. And will also make it easier to
merge page_mkwrite() with fault() in future.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Cc: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
Documentation/filesystems/Locking | 2 +-
drivers/video/fb_defio.c | 3 ++-
fs/buffer.c | 6 +++++-
fs/ext4/ext4.h | 2 +-
fs/ext4/inode.c | 5 ++++-
fs/fuse/file.c | 3 ++-
fs/gfs2/ops_file.c | 5 ++++-
fs/nfs/file.c | 5 ++++-
fs/ocfs2/mmap.c | 6 ++++--
fs/ubifs/file.c | 9 ++++++---
fs/xfs/linux-2.6/xfs_file.c | 4 ++--
include/linux/buffer_head.h | 2 +-
include/linux/mm.h | 3 ++-
mm/memory.c | 26 ++++++++++++++++++++++----
14 files changed, 60 insertions(+), 21 deletions(-)
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -502,7 +502,7 @@ prototypes:
void (*open)(struct vm_area_struct*);
void (*close)(struct vm_area_struct*);
int (*fault)(struct vm_area_struct*, struct vm_fault *);
- int (*page_mkwrite)(struct vm_area_struct *, struct page *);
+ int (*page_mkwrite)(struct vm_area_struct *, struct vm_fault *);
int (*access)(struct vm_area_struct *, unsigned long, void*, int, int);

locking rules:
--- a/drivers/video/fb_defio.c
+++ b/drivers/video/fb_defio.c
@@ -70,8 +70,9 @@ EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);

/* vm_ops->page_mkwrite handler */
static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
- struct page *page)
+ struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
struct fb_info *info = vma->vm_private_data;
struct fb_deferred_io *fbdefio = info->fbdefio;
struct page *cur;
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2402,9 +2402,10 @@ int block_commit_write(struct page *page
* unlock the page.
*/
int
-block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block)
{
+ struct page *page = vmf->page;
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
unsigned long end;
loff_t size;
@@ -2429,6 +2430,9 @@ block_page_mkwrite(struct vm_area_struct
ret = block_commit_write(page, 0, end);

out_unlock:
+ if (ret)
+ ret = VM_FAULT_SIGBUS;
+
unlock_page(page);
return ret;
}
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1084,7 +1084,7 @@ extern int ext4_meta_trans_blocks(struct
extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
extern int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from);
-extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page);
+extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);

/* ioctl.c */
extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4861,8 +4861,9 @@ static int ext4_bh_unmapped(handle_t *ha
return !buffer_mapped(bh);
}

-int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
loff_t size;
unsigned long len;
int ret = -EINVAL;
@@ -4913,6 +4914,8 @@ int ext4_page_mkwrite(struct vm_area_str
goto out_unlock;
ret = 0;
out_unlock:
+ if (ret)
+ ret = VM_FAULT_SIGBUS;
up_read(&inode->i_alloc_sem);
return ret;
}
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1219,8 +1219,9 @@ static void fuse_vma_close(struct vm_are
* - sync(2)
* - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
*/
-static int fuse_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+static int fuse_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
/*
* Don't use page->mapping as it may become NULL from a
* concurrent truncate.
--- a/fs/gfs2/ops_file.c
+++ b/fs/gfs2/ops_file.c
@@ -338,8 +338,9 @@ static int gfs2_allocate_page_backing(st
* blocks allocated on disk to back that page.
*/

-static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
@@ -411,6 +412,8 @@ out_unlock:
gfs2_glock_dq(&gh);
out:
gfs2_holder_uninit(&gh);
+ if (ret)
+ ret = VM_FAULT_SIGBUS;
return ret;
}

--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -448,8 +448,9 @@ const struct address_space_operations nf
.launder_page = nfs_launder_page,
};

-static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
struct file *filp = vma->vm_file;
struct dentry *dentry = filp->f_path.dentry;
unsigned pagelen;
@@ -480,6 +481,8 @@ static int nfs_vm_page_mkwrite(struct vm
ret = pagelen;
out_unlock:
unlock_page(page);
+ if (ret)
+ ret = VM_FAULT_SIGBUS;
return ret;
}

--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -150,8 +150,9 @@ out:
return ret;
}

-static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
struct buffer_head *di_bh = NULL;
sigset_t blocked, oldset;
@@ -192,7 +193,8 @@ out:
ret2 = ocfs2_vm_op_unblock_sigs(&oldset);
if (ret2 < 0)
mlog_errno(ret2);
-
+ if (ret)
+ ret = VM_FAULT_SIGBUS;
return ret;
}

--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1140,8 +1140,9 @@ static int ubifs_releasepage(struct page
* mmap()d file has taken write protection fault and is being made
* writable. UBIFS must ensure page is budgeted for.
*/
-static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ struct page *page = vmf->page;
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
struct ubifs_info *c = inode->i_sb->s_fs_info;
struct timespec now = ubifs_current_time(inode);
@@ -1153,7 +1154,7 @@ static int ubifs_vm_page_mkwrite(struct
ubifs_assert(!(inode->i_sb->s_flags & MS_RDONLY));

if (unlikely(c->ro_media))
- return -EROFS;
+ return VM_FAULT_SIGBUS; /* -EROFS */

/*
* We have not locked @page so far so we may budget for changing the
@@ -1186,7 +1187,7 @@ static int ubifs_vm_page_mkwrite(struct
if (err == -ENOSPC)
ubifs_warn("out of space for mmapped file "
"(inode number %lu)", inode->i_ino);
- return err;
+ return VM_FAULT_SIGBUS;
}

lock_page(page);
@@ -1226,6 +1227,8 @@ static int ubifs_vm_page_mkwrite(struct
out_unlock:
unlock_page(page);
ubifs_release_budget(c, &req);
+ if (err)
+ err = VM_FAULT_SIGBUS;
return err;
}

--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -427,9 +427,9 @@ xfs_file_ioctl_invis(
STATIC int
xfs_vm_page_mkwrite(
struct vm_area_struct *vma,
- struct page *page)
+ struct vm_fault *vmf)
{
- return block_page_mkwrite(vma, page, xfs_get_blocks);
+ return block_page_mkwrite(vma, vmf, xfs_get_blocks);
}

const struct file_operations xfs_file_operations = {
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -222,7 +222,7 @@ int cont_write_begin(struct file *, stru
get_block_t *, loff_t *);
int generic_cont_expand_simple(struct inode *inode, loff_t size);
int block_commit_write(struct page *page, unsigned from, unsigned to);
-int block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block);
void block_sync_page(struct page *);
sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -138,6 +138,7 @@ extern pgprot_t protection_map[16];

#define FAULT_FLAG_WRITE 0x01 /* Fault was a write access */
#define FAULT_FLAG_NONLINEAR 0x02 /* Fault was via a nonlinear mapping */
+#define FAULT_FLAG_MKWRITE 0x04 /* Fault was mkwrite of existing pte */


/*
@@ -173,7 +174,7 @@ struct vm_operations_struct {

/* notification that a previously read-only page is about to become
* writable, if an error is returned it will cause a SIGBUS */
- int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
+ int (*page_mkwrite)(struct vm_area_struct *vma, struct vm_fault *vmf);

/* called by access_process_vm when get_user_pages() fails, typically
* for use by special VMAs that can switch between memory and hardware
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1801,6 +1801,15 @@ static int do_wp_page(struct mm_struct *
* get_user_pages(.write=1, .force=1).
*/
if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
+ struct vm_fault vmf;
+ int tmp;
+
+ vmf.virtual_address = (void __user *)(address &
+ PAGE_MASK);
+ vmf.pgoff = old_page->index;
+ vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
+ vmf.page = old_page;
+
/*
* Notify the address space that the page is about to
* become writable so that it can prohibit this or wait
@@ -1812,8 +1821,12 @@ static int do_wp_page(struct mm_struct *
page_cache_get(old_page);
pte_unmap_unlock(page_table, ptl);

- if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
+ tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
+ if (unlikely(tmp &
+ (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
+ ret = tmp;
goto unwritable_page;
+ }

/*
* Since we dropped the lock we need to revalidate
@@ -1955,7 +1968,7 @@ oom:

unwritable_page:
page_cache_release(old_page);
- return VM_FAULT_SIGBUS;
+ return ret;
}

/*
@@ -2472,9 +2485,14 @@ static int __do_fault(struct mm_struct *
* to become writable
*/
if (vma->vm_ops->page_mkwrite) {
+ int tmp;
+
unlock_page(page);
- if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
- ret = VM_FAULT_SIGBUS;
+ vmf.flags |= FAULT_FLAG_MKWRITE;
+ tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
+ if (unlikely(tmp &
+ (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
+ ret = tmp;
anon = 1; /* no anon but release vmf.page */
goto out_unlocked;
}



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