btrfs_file_write -- first pass
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
David Woodhouse
parent
30ae846748
commit
75dfe3960e
222
fs/btrfs/super.c
222
fs/btrfs/super.c
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@ -9,6 +9,8 @@
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#include <linux/smp_lock.h>
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#include <linux/backing-dev.h>
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#include <linux/mpage.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include "ctree.h"
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#include "disk-io.h"
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#include "transaction.h"
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@ -755,7 +757,7 @@ printk("btrfs sync_fs\n");
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return 0;
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}
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static int btrfs_get_block(struct inode *inode, sector_t iblock,
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static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
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struct buffer_head *result, int create)
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{
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int ret;
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@ -772,7 +774,6 @@ static int btrfs_get_block(struct inode *inode, sector_t iblock,
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struct btrfs_disk_key *found_key;
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btrfs_init_path(&path);
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mutex_lock(&root->fs_info->fs_mutex);
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if (create)
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trans = btrfs_start_transaction(root, 1);
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@ -848,6 +849,16 @@ allocate:
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out:
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if (trans)
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btrfs_end_transaction(trans, root);
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return err;
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}
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static int btrfs_get_block(struct inode *inode, sector_t iblock,
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struct buffer_head *result, int create)
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{
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int err;
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struct btrfs_root *root = btrfs_sb(inode->i_sb);
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mutex_lock(&root->fs_info->fs_mutex);
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err = btrfs_get_block_lock(inode, iblock, result, create);
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mutex_unlock(&root->fs_info->fs_mutex);
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return err;
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}
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@ -855,8 +866,15 @@ out:
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static int btrfs_prepare_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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{
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WARN_ON(1);
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return nobh_prepare_write(page, from, to, btrfs_get_block);
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}
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static int btrfs_commit_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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{
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WARN_ON(1);
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return nobh_commit_write(file, page, from, to);
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}
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static void btrfs_write_super(struct super_block *sb)
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{
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@ -903,6 +921,196 @@ static void btrfs_truncate(struct inode *inode)
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mark_inode_dirty(inode);
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}
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static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
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struct page **prepared_pages,
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const char __user * buf)
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{
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long page_fault = 0;
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int i;
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int offset = pos & (PAGE_CACHE_SIZE - 1);
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for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
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size_t count = min_t(size_t,
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PAGE_CACHE_SIZE - offset, write_bytes);
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struct page *page = prepared_pages[i];
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fault_in_pages_readable(buf, count);
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/* Copy data from userspace to the current page */
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kmap(page);
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page_fault = __copy_from_user(page_address(page) + offset,
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buf, count);
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/* Flush processor's dcache for this page */
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flush_dcache_page(page);
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kunmap(page);
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buf += count;
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write_bytes -= count;
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if (page_fault)
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break;
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}
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return page_fault ? -EFAULT : 0;
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}
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static void btrfs_drop_pages(struct page **pages, size_t num_pages)
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{
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size_t i;
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for (i = 0; i < num_pages; i++) {
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if (!pages[i])
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break;
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unlock_page(pages[i]);
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mark_page_accessed(pages[i]);
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page_cache_release(pages[i]);
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}
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}
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static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct file *file,
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struct page **pages,
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size_t num_pages,
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loff_t pos,
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size_t write_bytes)
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{
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int i;
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int offset;
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int err = 0;
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int ret;
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int this_write;
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for (i = 0; i < num_pages; i++) {
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offset = pos & (PAGE_CACHE_SIZE -1);
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this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
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ret = nobh_commit_write(file, pages[i], offset,
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offset + this_write);
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pos += this_write;
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if (ret) {
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err = ret;
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goto failed;
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}
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WARN_ON(this_write > write_bytes);
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write_bytes -= this_write;
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}
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failed:
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return err;
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}
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static int prepare_pages(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct file *file,
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struct page **pages,
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size_t num_pages,
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loff_t pos,
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size_t write_bytes)
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{
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int i;
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unsigned long index = pos >> PAGE_CACHE_SHIFT;
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struct inode *inode = file->f_path.dentry->d_inode;
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int offset;
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int err = 0;
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int ret;
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int this_write;
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loff_t isize = i_size_read(inode);
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memset(pages, 0, num_pages * sizeof(struct page *));
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for (i = 0; i < num_pages; i++) {
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pages[i] = grab_cache_page(inode->i_mapping, index + i);
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if (!pages[i]) {
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err = -ENOMEM;
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goto failed_release;
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}
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offset = pos & (PAGE_CACHE_SIZE -1);
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this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
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ret = nobh_prepare_write(pages[i], offset,
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offset + this_write,
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btrfs_get_block_lock);
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pos += this_write;
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if (ret) {
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err = ret;
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goto failed_truncate;
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}
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WARN_ON(this_write > write_bytes);
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write_bytes -= this_write;
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}
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return 0;
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failed_release:
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btrfs_drop_pages(pages, num_pages);
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return err;
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failed_truncate:
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btrfs_drop_pages(pages, num_pages);
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if (pos > isize)
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vmtruncate(inode, isize);
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return err;
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}
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static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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loff_t pos;
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size_t num_written = 0;
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int err = 0;
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int ret = 0;
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struct btrfs_trans_handle *trans;
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struct inode *inode = file->f_path.dentry->d_inode;
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struct btrfs_root *root = btrfs_sb(inode->i_sb);
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struct page *pages[1];
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if (file->f_flags & O_DIRECT)
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return -EINVAL;
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pos = *ppos;
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vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
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current->backing_dev_info = inode->i_mapping->backing_dev_info;
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err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
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if (err)
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goto out;
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if (count == 0)
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goto out;
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err = remove_suid(file->f_path.dentry);
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if (err)
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goto out;
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file_update_time(file);
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mutex_lock(&inode->i_mutex);
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while(count > 0) {
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size_t offset = pos & (PAGE_CACHE_SIZE - 1);
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size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
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size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
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PAGE_CACHE_SHIFT;
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mutex_lock(&root->fs_info->fs_mutex);
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trans = btrfs_start_transaction(root, 1);
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ret = prepare_pages(trans, root, file, pages, num_pages,
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pos, write_bytes);
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BUG_ON(ret);
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ret = btrfs_copy_from_user(pos, num_pages,
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write_bytes, pages, buf);
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BUG_ON(ret);
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mutex_unlock(&root->fs_info->fs_mutex);
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ret = dirty_and_release_pages(trans, root, file, pages,
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num_pages, pos, write_bytes);
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BUG_ON(ret);
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btrfs_drop_pages(pages, num_pages);
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ret = btrfs_end_transaction(trans, root);
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buf += write_bytes;
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count -= write_bytes;
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pos += write_bytes;
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num_written += write_bytes;
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balance_dirty_pages_ratelimited(inode->i_mapping);
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cond_resched();
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}
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mutex_unlock(&inode->i_mutex);
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out:
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*ppos = pos;
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current->backing_dev_info = NULL;
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return num_written ? num_written : err;
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}
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static int btrfs_get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data, struct vfsmount *mnt)
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{
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@ -948,7 +1156,7 @@ static struct address_space_operations btrfs_aops = {
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.writepage = btrfs_writepage,
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.sync_page = block_sync_page,
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.prepare_write = btrfs_prepare_write,
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.commit_write = nobh_commit_write,
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.commit_write = btrfs_commit_write,
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};
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static struct inode_operations btrfs_file_inode_operations = {
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@ -958,14 +1166,10 @@ static struct inode_operations btrfs_file_inode_operations = {
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static struct file_operations btrfs_file_operations = {
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.llseek = generic_file_llseek,
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.read = do_sync_read,
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.write = do_sync_write,
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.aio_read = generic_file_aio_read,
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.aio_write = generic_file_aio_write,
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.aio_read = generic_file_aio_read,
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.write = btrfs_file_write,
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.mmap = generic_file_mmap,
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.open = generic_file_open,
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.sendfile = generic_file_sendfile,
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.splice_read = generic_file_splice_read,
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.splice_write = generic_file_splice_write,
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};
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static int __init init_btrfs_fs(void)
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