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Btrfs: when forced to cow for file_write, get the page uptodate first 

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2007-04-10 14:22:02 -04:00 committed by David Woodhouse
parent 79b2cb1fa6
commit 2932f3ec94
1 changed files with 14 additions and 1 deletions
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15
fs/btrfs/super.c
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@ -1268,6 +1268,8 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
struct page **pages,
size_t num_pages,
loff_t pos,
unsigned long first_index,
unsigned long last_index,
size_t write_bytes)
{
int i;
@ -1289,6 +1291,13 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
}
offset = pos & (PAGE_CACHE_SIZE -1);
this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
if (!PageUptodate(pages[i]) &&
(pages[i]->index == first_index ||
pages[i]->index == last_index) && pos < isize) {
ret = mpage_readpage(pages[i], btrfs_get_block);
BUG_ON(ret);
lock_page(pages[i]);
}
ret = nobh_prepare_write(pages[i], offset,
offset + this_write,
btrfs_get_block);
@ -1323,6 +1332,8 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
struct inode *inode = file->f_path.dentry->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct page *pages[1];
unsigned long first_index;
unsigned long last_index;
if (file->f_flags & O_DIRECT)
return -EINVAL;
@ -1340,13 +1351,15 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
goto out;
file_update_time(file);
mutex_lock(&inode->i_mutex);
first_index = pos >> PAGE_CACHE_SHIFT;
last_index = (pos + count) >> PAGE_CACHE_SHIFT;
while(count > 0) {
size_t offset = pos & (PAGE_CACHE_SIZE - 1);
size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT;
ret = prepare_pages(NULL, root, file, pages, num_pages,
pos, write_bytes);
pos, first_index, last_index, write_bytes);
BUG_ON(ret);
ret = btrfs_copy_from_user(pos, num_pages,
write_bytes, pages, buf);