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![Josef Bacik](/assets/img/avatar_default.png)
Btrfs needs to be able to control how filemap_write_and_wait_range() is called in fsync to make it less of a painful operation, so push down taking i_mutex and the calling of filemap_write_and_wait() down into the ->fsync() handlers. Some file systems can drop taking the i_mutex altogether it seems, like ext3 and ocfs2. For correctness sake I just pushed everything down in all cases to make sure that we keep the current behavior the same for everybody, and then each individual fs maintainer can make up their mind about what to do from there. Thanks, Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
284 lines
7.1 KiB
C
284 lines
7.1 KiB
C
/*
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* fs/logfs/file.c - prepare_write, commit_write and friends
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*
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* As should be obvious for Linux kernel code, license is GPLv2
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*
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* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
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*/
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#include "logfs.h"
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#include <linux/sched.h>
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#include <linux/writeback.h>
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static int logfs_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata)
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{
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struct inode *inode = mapping->host;
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struct page *page;
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pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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page = grab_cache_page_write_begin(mapping, index, flags);
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if (!page)
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return -ENOMEM;
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*pagep = page;
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if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
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return 0;
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if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
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unsigned start = pos & (PAGE_CACHE_SIZE - 1);
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unsigned end = start + len;
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/* Reading beyond i_size is simple: memset to zero */
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zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
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return 0;
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}
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return logfs_readpage_nolock(page);
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}
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static int logfs_write_end(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied, struct page *page,
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void *fsdata)
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{
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struct inode *inode = mapping->host;
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pgoff_t index = page->index;
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unsigned start = pos & (PAGE_CACHE_SIZE - 1);
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unsigned end = start + copied;
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int ret = 0;
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BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
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BUG_ON(page->index > I3_BLOCKS);
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if (copied < len) {
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/*
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* Short write of a non-initialized paged. Just tell userspace
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* to retry the entire page.
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*/
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if (!PageUptodate(page)) {
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copied = 0;
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goto out;
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}
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}
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if (copied == 0)
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goto out; /* FIXME: do we need to update inode? */
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if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
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i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
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mark_inode_dirty_sync(inode);
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}
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SetPageUptodate(page);
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if (!PageDirty(page)) {
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if (!get_page_reserve(inode, page))
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__set_page_dirty_nobuffers(page);
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else
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ret = logfs_write_buf(inode, page, WF_LOCK);
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}
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out:
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unlock_page(page);
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page_cache_release(page);
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return ret ? ret : copied;
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}
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int logfs_readpage(struct file *file, struct page *page)
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{
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int ret;
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ret = logfs_readpage_nolock(page);
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unlock_page(page);
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return ret;
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}
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/* Clear the page's dirty flag in the radix tree. */
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/* TODO: mucking with PageWriteback is silly. Add a generic function to clear
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* the dirty bit from the radix tree for filesystems that don't have to wait
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* for page writeback to finish (i.e. any compressing filesystem).
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*/
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static void clear_radix_tree_dirty(struct page *page)
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{
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BUG_ON(PagePrivate(page) || page->private);
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set_page_writeback(page);
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end_page_writeback(page);
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}
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static int __logfs_writepage(struct page *page)
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{
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struct inode *inode = page->mapping->host;
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int err;
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err = logfs_write_buf(inode, page, WF_LOCK);
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if (err)
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set_page_dirty(page);
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else
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clear_radix_tree_dirty(page);
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unlock_page(page);
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return err;
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}
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static int logfs_writepage(struct page *page, struct writeback_control *wbc)
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{
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struct inode *inode = page->mapping->host;
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loff_t i_size = i_size_read(inode);
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pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
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unsigned offset;
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u64 bix;
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level_t level;
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log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
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page);
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logfs_unpack_index(page->index, &bix, &level);
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/* Indirect blocks are never truncated */
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if (level != 0)
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return __logfs_writepage(page);
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/*
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* TODO: everything below is a near-verbatim copy of nobh_writepage().
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* The relevant bits should be factored out after logfs is merged.
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*/
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/* Is the page fully inside i_size? */
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if (bix < end_index)
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return __logfs_writepage(page);
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/* Is the page fully outside i_size? (truncate in progress) */
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offset = i_size & (PAGE_CACHE_SIZE-1);
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if (bix > end_index || offset == 0) {
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unlock_page(page);
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return 0; /* don't care */
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}
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/*
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* The page straddles i_size. It must be zeroed out on each and every
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* writepage invokation because it may be mmapped. "A file is mapped
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* in multiples of the page size. For a file that is not a multiple of
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* the page size, the remaining memory is zeroed when mapped, and
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* writes to that region are not written out to the file."
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*/
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zero_user_segment(page, offset, PAGE_CACHE_SIZE);
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return __logfs_writepage(page);
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}
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static void logfs_invalidatepage(struct page *page, unsigned long offset)
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{
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struct logfs_block *block = logfs_block(page);
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if (block->reserved_bytes) {
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struct super_block *sb = page->mapping->host->i_sb;
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struct logfs_super *super = logfs_super(sb);
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super->s_dirty_pages -= block->reserved_bytes;
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block->ops->free_block(sb, block);
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BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
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} else
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move_page_to_btree(page);
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BUG_ON(PagePrivate(page) || page->private);
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}
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static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
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{
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return 0; /* None of these are easy to release */
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}
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long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct inode *inode = file->f_path.dentry->d_inode;
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struct logfs_inode *li = logfs_inode(inode);
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unsigned int oldflags, flags;
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int err;
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switch (cmd) {
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case FS_IOC_GETFLAGS:
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flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
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return put_user(flags, (int __user *)arg);
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case FS_IOC_SETFLAGS:
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if (IS_RDONLY(inode))
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return -EROFS;
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if (!inode_owner_or_capable(inode))
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return -EACCES;
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err = get_user(flags, (int __user *)arg);
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if (err)
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return err;
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mutex_lock(&inode->i_mutex);
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oldflags = li->li_flags;
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flags &= LOGFS_FL_USER_MODIFIABLE;
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flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
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li->li_flags = flags;
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mutex_unlock(&inode->i_mutex);
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inode->i_ctime = CURRENT_TIME;
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mark_inode_dirty_sync(inode);
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return 0;
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default:
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return -ENOTTY;
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}
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}
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int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
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{
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struct super_block *sb = file->f_mapping->host->i_sb;
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struct inode *inode = file->f_mapping->host;
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int ret;
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ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
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if (ret)
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return ret;
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mutex_lock(&inode->i_mutex);
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logfs_write_anchor(sb);
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mutex_unlock(&inode->i_mutex);
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return 0;
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}
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static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
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{
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struct inode *inode = dentry->d_inode;
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int err = 0;
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err = inode_change_ok(inode, attr);
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if (err)
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return err;
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if (attr->ia_valid & ATTR_SIZE) {
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err = logfs_truncate(inode, attr->ia_size);
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if (err)
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return err;
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}
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setattr_copy(inode, attr);
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mark_inode_dirty(inode);
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return 0;
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}
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const struct inode_operations logfs_reg_iops = {
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.setattr = logfs_setattr,
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};
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const struct file_operations logfs_reg_fops = {
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.aio_read = generic_file_aio_read,
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.aio_write = generic_file_aio_write,
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.fsync = logfs_fsync,
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.unlocked_ioctl = logfs_ioctl,
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.llseek = generic_file_llseek,
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.mmap = generic_file_readonly_mmap,
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.open = generic_file_open,
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.read = do_sync_read,
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.write = do_sync_write,
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};
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const struct address_space_operations logfs_reg_aops = {
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.invalidatepage = logfs_invalidatepage,
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.readpage = logfs_readpage,
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.releasepage = logfs_releasepage,
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.set_page_dirty = __set_page_dirty_nobuffers,
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.writepage = logfs_writepage,
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.writepages = generic_writepages,
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.write_begin = logfs_write_begin,
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.write_end = logfs_write_end,
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};
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