struct buffer_head *nilfs_grab_buffer(struct inode *inode,
struct address_space *mapping,
unsigned long blkoff,
unsigned long b_state)
{
int blkbits = inode->i_blkbits;
pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
struct page *page, *opage;
struct buffer_head *bh, *obh;
page = grab_cache_page(mapping, index);
if (unlikely(!page))
return NULL;
bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
if (unlikely(!bh)) {
unlock_page(page);
page_cache_release(page);
return NULL;
}
if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
/*
* Shadow page cache uses assoc_mapping to point its original
* page cache. The following code tries the original cache
* if the given cache is a shadow and it didn't hit.
*/
opage = find_lock_page(mapping->assoc_mapping, index);
if (!opage)
return bh;
obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
b_state);
if (buffer_uptodate(obh)) {
nilfs_copy_buffer(bh, obh);
if (buffer_dirty(obh)) {
nilfs_mark_buffer_dirty(bh);
if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
nilfs_mdt_mark_dirty(inode);
}
}
brelse(obh);
unlock_page(opage);
page_cache_release(opage);
}
return bh;
}
struct buffer_head *nilfs_grab_buffer(struct inode *inode,
struct address_space *mapping,
unsigned long blkoff,
unsigned long b_state)
{
int blkbits = inode->i_blkbits;
pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
struct page *page;
struct buffer_head *bh;
page = grab_cache_page(mapping, index);
if (unlikely(!page))
return NULL;
bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
if (unlikely(!bh)) {
unlock_page(page);
put_page(page);
return NULL;
}
return bh;
}