[rfc][patch 3/3] fs: convert ext2,tmpfs to new truncate

Nick Piggin
2009-07-06T16:18:36Z

Convert filemap_xip.c, buffer.c, and some filesystems to the new truncate
convention. Converting generic helpers is using some ugly code (testing
for i_op->ftruncate) to distinguish new and old callers... better
alternative might be just define a new function for these guys.
---
fs/buffer.c | 40 +++++++++++++++++--------
fs/ext2/ext2.h | 2 -
fs/ext2/file.c | 2 -
fs/ext2/inode.c | 85 ++++++++++++++++++++++++++++++++++++++++++-------------
mm/filemap_xip.c | 15 +++++++--
mm/shmem.c | 40 ++++++++++++++++---------
6 files changed, 133 insertions(+), 51 deletions(-)

Index: linux-2.6/fs/ext2/inode.c
===================================================================
--- linux-2.6.orig/fs/ext2/inode.c
+++ linux-2.6/fs/ext2/inode.c
@@ -68,7 +68,7 @@ void ext2_delete_inode (struct inode * i

inode->i_size = 0;
if (inode->i_blocks)
- ext2_truncate (inode);
+ ext2_ftruncate(NULL, 0, inode, 0);
ext2_free_inode (inode);

return;
@@ -761,8 +761,31 @@ ext2_write_begin(struct file *file, stru
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
+ int ret;
+
*pagep = NULL;
- return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
+ ret = __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
+ if (ret < 0) {
+ loff_t isize = inode->i_size;
+ if (pos + len > isize)
+ ext2_ftruncate(NULL, 0, inode, isize);
+ }
+ return ret;
+}
+
+static int ext2_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ int ret;
+
+ ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
+ if (ret < len) {
+ loff_t isize = inode->i_size;
+ if (pos + len > isize)
+ ext2_ftruncate(NULL, 0, inode, isize);
+ }
+ return ret;
}

static int
@@ -770,13 +793,22 @@ ext2_nobh_write_begin(struct file *file,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
+ int ret;
+
/*
* Dir-in-pagecache still uses ext2_write_begin. Would have to rework
* directory handling code to pass around offsets rather than struct
* pages in order to make this work easily.
*/
- return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+ ret = nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
ext2_get_block);
+ if (ret < 0) {
+ loff_t isize;
+ isize = i_size_read(inode);
+ if (pos + len > isize)
+ ext2_ftruncate(NULL, 0, inode, isize);
+ }
+ return ret;
}

static int ext2_nobh_writepage(struct page *page,
@@ -796,9 +828,15 @@ ext2_direct_IO(int rw, struct kiocb *ioc
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
+ ssize_t ret;

- return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
+ ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
offset, nr_segs, ext2_get_block, NULL);
+ if (ret < 0 && (rw & WRITE)) {
+ loff_t isize = i_size_read(inode);
+ ext2_ftruncate(NULL, 0, inode, isize);
+ }
+ return ret;
}

static int
@@ -813,7 +851,7 @@ const struct address_space_operations ex
.writepage = ext2_writepage,
.sync_page = block_sync_page,
.write_begin = ext2_write_begin,
- .write_end = generic_write_end,
+ .write_end = ext2_write_end,
.bmap = ext2_bmap,
.direct_IO = ext2_direct_IO,
.writepages = ext2_writepages,
@@ -1020,7 +1058,8 @@ static void ext2_free_branches(struct in
ext2_free_data(inode, p, q);
}

-void ext2_truncate(struct inode *inode)
+int ext2_ftruncate(struct file *file, int open,
+ struct inode *inode, loff_t offset)
{
__le32 *i_data = EXT2_I(inode)->i_data;
struct ext2_inode_info *ei = EXT2_I(inode);
@@ -1032,31 +1071,37 @@ void ext2_truncate(struct inode *inode)
int n;
long iblock;
unsigned blocksize;
+ int error;
+
+ error = inode_truncate_ok(inode, offset);
+ if (error)
+ return error;

if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
S_ISLNK(inode->i_mode)))
- return;
+ return -EINVAL;
if (ext2_inode_is_fast_symlink(inode))
- return;
+ return -EINVAL;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
- return;
-
- blocksize = inode->i_sb->s_blocksize;
- iblock = (inode->i_size + blocksize-1)
- >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
+ return -EPERM;

if (mapping_is_xip(inode->i_mapping))
- xip_truncate_page(inode->i_mapping, inode->i_size);
+ error = xip_truncate_page(inode->i_mapping, offset);
else if (test_opt(inode->i_sb, NOBH))
- nobh_truncate_page(inode->i_mapping,
- inode->i_size, ext2_get_block);
+ error = nobh_truncate_page(inode->i_mapping,
+ offset, ext2_get_block);
else
- block_truncate_page(inode->i_mapping,
- inode->i_size, ext2_get_block);
+ error = block_truncate_page(inode->i_mapping,
+ offset, ext2_get_block);
+ if (error)
+ return error;
+
+ blocksize = inode->i_sb->s_blocksize;
+ iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);

n = ext2_block_to_path(inode, iblock, offsets, NULL);
if (n == 0)
- return;
+ return 0;

/*
* From here we block out all ext2_get_block() callers who want to
@@ -1127,6 +1172,8 @@ do_indirects:
} else {
mark_inode_dirty(inode);
}
+
+ return 0;
}

static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c
+++ linux-2.6/mm/shmem.c
@@ -730,10 +730,11 @@ done2:
if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
/*
* Call truncate_inode_pages again: racing shmem_unuse_inode
- * may have swizzled a page in from swap since vmtruncate or
- * generic_delete_inode did it, before we lowered next_index.
- * Also, though shmem_getpage checks i_size before adding to
- * cache, no recheck after: so fix the narrow window there too.
+ * may have swizzled a page in from swap since
+ * truncate_pagecache or generic_delete_inode did it, before we
+ * lowered next_index. Also, though shmem_getpage checks
+ * i_size before adding to cache, no recheck after: so fix the
+ * narrow window there too.
*
* Recalling truncate_inode_pages_range and unmap_mapping_range
* every time for punch_hole (which never got a chance to clear
@@ -763,9 +764,21 @@ done2:
}
}

-static void shmem_truncate(struct inode *inode)
+static int shmem_ftruncate(struct file *file, int open,
+ struct inode *inode, loff_t offset)
{
- shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
+ loff_t oldsize;
+ int error;
+
+ error = inode_truncate_ok(inode, offset);
+ if (error)
+ return error;
+ oldsize = inode->i_size;
+ i_size_write(inode, offset);
+ truncate_pagecache(inode, oldsize, offset);
+ shmem_truncate_range(inode, offset, (loff_t)-1);
+
+ return error;
}

static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
@@ -822,11 +835,10 @@ static void shmem_delete_inode(struct in
{
struct shmem_inode_info *info = SHMEM_I(inode);

- if (inode->i_op->truncate == shmem_truncate) {
+ if (inode->i_op->ftruncate == shmem_ftruncate) {
truncate_inode_pages(inode->i_mapping, 0);
shmem_unacct_size(info->flags, inode->i_size);
- inode->i_size = 0;
- shmem_truncate(inode);
+ shmem_ftruncate(NULL, 0, inode, 0);
if (!list_empty(&info->swaplist)) {
mutex_lock(&shmem_swaplist_mutex);
list_del_init(&info->swaplist);
@@ -1627,13 +1639,13 @@ shmem_write_end(struct file *file, struc
{
struct inode *inode = mapping->host;

- if (pos + copied > inode->i_size)
- i_size_write(inode, pos + copied);
-
unlock_page(page);
set_page_dirty(page);
page_cache_release(page);

+ if (pos + copied > inode->i_size)
+ i_size_write(inode, pos + copied);
+
return copied;
}

@@ -2018,7 +2030,7 @@ static const struct inode_operations shm
};

static const struct inode_operations shmem_symlink_inode_operations = {
- .truncate = shmem_truncate,
+ .ftruncate = shmem_ftruncate,
.readlink = generic_readlink,
.follow_link = shmem_follow_link,
.put_link = shmem_put_link,
@@ -2438,7 +2450,7 @@ static const struct file_operations shme
};

static const struct inode_operations shmem_inode_operations = {
- .truncate = shmem_truncate,
+ .ftruncate = shmem_ftruncate,
.setattr = shmem_notify_change,
.truncate_range = shmem_truncate_range,
#ifdef CONFIG_TMPFS_POSIX_ACL
Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -2702,22 +2702,23 @@ int nobh_truncate_page(struct address_sp
struct inode *inode = mapping->host;
struct page *page;
struct buffer_head map_bh;
- int err;
+ int err = 0;

blocksize = 1 << inode->i_blkbits;
length = offset & (blocksize - 1);

/* Block boundary? Nothing to do */
if (!length)
- return 0;
+ goto out;

length = blocksize - length;
iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);

page = grab_cache_page(mapping, index);
- err = -ENOMEM;
- if (!page)
+ if (!page) {
+ err = -ENOMEM;
goto out;
+ }

if (page_has_buffers(page)) {
has_buffers:
@@ -2759,12 +2760,18 @@ has_buffers:
}
zero_user(page, offset, length);
set_page_dirty(page);
- err = 0;

unlock:
unlock_page(page);
page_cache_release(page);
out:
+ if (!err && inode->i_op->ftruncate) {
+ loff_t oldsize = inode->i_size;
+
+ i_size_write(inode, from);
+ truncate_pagecache(inode, oldsize, from);
+ }
+
return err;
}
EXPORT_SYMBOL(nobh_truncate_page);
@@ -2780,22 +2787,23 @@ int block_truncate_page(struct address_s
struct inode *inode = mapping->host;
struct page *page;
struct buffer_head *bh;
- int err;
+ int err = 0;

blocksize = 1 << inode->i_blkbits;
length = offset & (blocksize - 1);

/* Block boundary? Nothing to do */
if (!length)
- return 0;
+ goto out;

length = blocksize - length;
iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);

page = grab_cache_page(mapping, index);
- err = -ENOMEM;
- if (!page)
+ if (!page) {
+ err = -ENOMEM;
goto out;
+ }

if (!page_has_buffers(page))
create_empty_buffers(page, blocksize, 0);
@@ -2809,7 +2817,6 @@ int block_truncate_page(struct address_s
pos += blocksize;
}

- err = 0;
if (!buffer_mapped(bh)) {
WARN_ON(bh->b_size != blocksize);
err = get_block(inode, iblock, bh, 0);
@@ -2825,22 +2832,29 @@ int block_truncate_page(struct address_s
set_buffer_uptodate(bh);

if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
- err = -EIO;
ll_rw_block(READ, 1, &bh);
wait_on_buffer(bh);
/* Uhhuh. Read error. Complain and punt. */
- if (!buffer_uptodate(bh))
+ if (!buffer_uptodate(bh)) {
+ err = -EIO;
goto unlock;
+ }
}

zero_user(page, offset, length);
mark_buffer_dirty(bh);
- err = 0;

unlock:
unlock_page(page);
page_cache_release(page);
out:
+ if (!err && inode->i_op->ftruncate) {
+ loff_t oldsize = inode->i_size;
+
+ i_size_write(inode, from);
+ truncate_pagecache(inode, oldsize, from);
+ }
+
return err;
}

Index: linux-2.6/fs/ext2/ext2.h
===================================================================
--- linux-2.6.orig/fs/ext2/ext2.h
+++ linux-2.6/fs/ext2/ext2.h
@@ -122,7 +122,7 @@ extern int ext2_write_inode (struct inod
extern void ext2_delete_inode (struct inode *);
extern int ext2_sync_inode (struct inode *);
extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
-extern void ext2_truncate (struct inode *);
+extern int ext2_ftruncate(struct file *, int, struct inode *, loff_t);
extern int ext2_setattr (struct dentry *, struct iattr *);
extern void ext2_set_inode_flags(struct inode *inode);
extern void ext2_get_inode_flags(struct ext2_inode_info *);
Index: linux-2.6/mm/filemap_xip.c
===================================================================
--- linux-2.6.orig/mm/filemap_xip.c
+++ linux-2.6/mm/filemap_xip.c
@@ -440,7 +440,9 @@ EXPORT_SYMBOL_GPL(xip_file_write);
int
xip_truncate_page(struct address_space *mapping, loff_t from)
{
+ struct inode *inode = mapping->host;
pgoff_t index = from >> PAGE_CACHE_SHIFT;
+ loff_t oldsize;
unsigned offset = from & (PAGE_CACHE_SIZE-1);
unsigned blocksize;
unsigned length;
@@ -450,12 +452,12 @@ xip_truncate_page(struct address_space *

BUG_ON(!mapping->a_ops->get_xip_mem);

- blocksize = 1 << mapping->host->i_blkbits;
+ blocksize = 1 << inode->i_blkbits;
length = offset & (blocksize - 1);

/* Block boundary? Nothing to do */
if (!length)
- return 0;
+ goto out;

length = blocksize - length;

@@ -464,11 +466,18 @@ xip_truncate_page(struct address_space *
if (unlikely(err)) {
if (err == -ENODATA)
/* Hole? No need to truncate */
- return 0;
+ goto out;
else
return err;
}
memset(xip_mem + offset, 0, length);
+out:
+ if (inode->i_op->ftruncate) {
+ oldsize = inode->i_size;
+ i_size_write(inode, from);
+ truncate_pagecache(inode, oldsize, from);
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(xip_truncate_page);
Index: linux-2.6/fs/ext2/file.c
===================================================================
--- linux-2.6.orig/fs/ext2/file.c
+++ linux-2.6/fs/ext2/file.c
@@ -77,7 +77,7 @@ const struct file_operations ext2_xip_fi
#endif

const struct inode_operations ext2_file_inode_operations = {
- .truncate = ext2_truncate,
+ .ftruncate = ext2_ftruncate,
#ifdef CONFIG_EXT2_FS_XATTR
.setxattr = generic_setxattr,
.getxattr = generic_getxattr,