From ccd2506bd43113659aa904d5bea5d1300605e2a6 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Thu, 26 Feb 2009 01:04:07 -0500 Subject: ext4: add EXT4_IOC_ALLOC_DA_BLKS ioctl Add an ioctl which forces all of the delay allocated blocks to be allocated. This also provides a function ext4_alloc_da_blocks() which will be used by the following commits to force files to be fully allocated to preserve application-expected ext3 behaviour. Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) (limited to 'fs/ext4/inode.c') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 24d0f9d2b320..8dd3d5de5861 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2837,6 +2837,48 @@ out: return; } +/* + * Force all delayed allocation blocks to be allocated for a given inode. + */ +int ext4_alloc_da_blocks(struct inode *inode) +{ + if (!EXT4_I(inode)->i_reserved_data_blocks && + !EXT4_I(inode)->i_reserved_meta_blocks) + return 0; + + /* + * We do something simple for now. The filemap_flush() will + * also start triggering a write of the data blocks, which is + * not strictly speaking necessary (and for users of + * laptop_mode, not even desirable). However, to do otherwise + * would require replicating code paths in: + * + * ext4_da_writepages() -> + * write_cache_pages() ---> (via passed in callback function) + * __mpage_da_writepage() --> + * mpage_add_bh_to_extent() + * mpage_da_map_blocks() + * + * The problem is that write_cache_pages(), located in + * mm/page-writeback.c, marks pages clean in preparation for + * doing I/O, which is not desirable if we're not planning on + * doing I/O at all. + * + * We could call write_cache_pages(), and then redirty all of + * the pages by calling redirty_page_for_writeback() but that + * would be ugly in the extreme. So instead we would need to + * replicate parts of the code in the above functions, + * simplifying them becuase we wouldn't actually intend to + * write out the pages, but rather only collect contiguous + * logical block extents, call the multi-block allocator, and + * then update the buffer heads with the block allocations. + * + * For now, though, we'll cheat by calling filemap_flush(), + * which will map the blocks, and start the I/O, but not + * actually wait for the I/O to complete. + */ + return filemap_flush(inode->i_mapping); +} /* * bmap() is special. It gets used by applications such as lilo and by -- cgit v1.2.2