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Commit 79ffab34 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Theodore Ts'o
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ext4: Properly initialize the buffer_head state 



These struct buffer_heads are allocated on the stack (and hence are
initialized with stack garbage).  They are only used to call a
get_blocks() function, so that's mostly OK, but b_state must be
initialized to be 0 so we don't have any unexpected BH_* flags set by
accident, such as BH_Unwritten or BH_Delay.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 9fa7eb28

fs/ext4/extents.c

+1 −0
Original line number Diff line number Diff line
@@ -3150,6 +3150,7 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len) 
			ret = PTR_ERR(handle);

			break;

		}

		map_bh.b_state = 0;

		ret = ext4_get_blocks_wrap(handle, inode, block,

					  max_blocks, &map_bh,

					  EXT4_CREATE_UNINITIALIZED_EXT, 0, 0);

fs/ext4/inode.c

+14 −1
Original line number Diff line number Diff line
@@ -2055,7 +2055,20 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 
	if ((mpd->b_state  & (1 << BH_Mapped)) &&

	    !(mpd->b_state & (1 << BH_Delay)))

		return 0;

	new.b_state = mpd->b_state;

	/*

	 * We need to make sure the BH_Delay flag is passed down to

	 * ext4_da_get_block_write(), since it calls

	 * ext4_get_blocks_wrap() with the EXT4_DELALLOC_RSVED flag.

	 * This flag causes ext4_get_blocks_wrap() to call

	 * ext4_da_update_reserve_space() if the passed buffer head

	 * has the BH_Delay flag set.  In the future, once we clean up

	 * the interfaces to ext4_get_blocks_wrap(), we should pass in

	 * a separate flag which requests that the delayed allocation

	 * statistics should be updated, instead of depending on the

	 * state information getting passed down via the map_bh's

	 * state bitmasks plus the magic EXT4_DELALLOC_RSVED flag.

	 */

	new.b_state = mpd->b_state & (1 << BH_Delay);

	new.b_blocknr = 0;

	new.b_size = mpd->b_size;

	next = mpd->b_blocknr;

fs/mpage.c

+4 −2
Original line number Diff line number Diff line
@@ -379,7 +379,8 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages, 
	struct buffer_head map_bh;

	unsigned long first_logical_block = 0;



	clear_buffer_mapped(&map_bh);

	map_bh.b_state = 0;

	map_bh.b_size = 0;

	for (page_idx = 0; page_idx < nr_pages; page_idx++) {

		struct page *page = list_entry(pages->prev, struct page, lru);
@@ -412,7 +413,8 @@ int mpage_readpage(struct page *page, get_block_t get_block) 
	struct buffer_head map_bh;

	unsigned long first_logical_block = 0;



	clear_buffer_mapped(&map_bh);

	map_bh.b_state = 0;

	map_bh.b_size = 0;

	bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,

			&map_bh, &first_logical_block, get_block);

	if (bio)