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

Boaz Harrosh
2009-07-07T11:45:22Z

On 07/06/2009 07:56 PM, Nick Piggin wrote:
> 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);

Unlike the other places you use i_size_read() here, please explain what is the
locking rules for this?

Did your patchset change things in this regard?

> + 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,
> --
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