Btrfs: when forced to cow for file_write, get the page uptodate first
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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@ -1268,6 +1268,8 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
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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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unsigned long first_index,
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unsigned long last_index,
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size_t write_bytes)
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{
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int i;
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@ -1289,6 +1291,13 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
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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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if (!PageUptodate(pages[i]) &&
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(pages[i]->index == first_index ||
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pages[i]->index == last_index) && pos < isize) {
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ret = mpage_readpage(pages[i], btrfs_get_block);
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BUG_ON(ret);
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lock_page(pages[i]);
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}
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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);
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@ -1323,6 +1332,8 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
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struct inode *inode = file->f_path.dentry->d_inode;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct page *pages[1];
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unsigned long first_index;
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unsigned long last_index;
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if (file->f_flags & O_DIRECT)
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return -EINVAL;
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@ -1340,13 +1351,15 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
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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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first_index = pos >> PAGE_CACHE_SHIFT;
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last_index = (pos + count) >> PAGE_CACHE_SHIFT;
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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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ret = prepare_pages(NULL, root, file, pages, num_pages,
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pos, write_bytes);
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pos, first_index, last_index, 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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