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Commit 2ac3b6e0 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: Clean up ext4_get_blocks() so it does not depend on bh_result->b_state 



The ext4_get_blocks() function was depending on the value of
bh_result->b_state as an input parameter to decide whether or not
update the delalloc accounting statistics by calling
ext4_da_update_reserve_space().  We now use a separate flag,
EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE, to requests this update, so that
all callers of ext4_get_blocks() can clear map_bh.b_state before
calling ext4_get_blocks() without worrying about any consistency
issues.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 2fa3cdfb

fs/ext4/ext4.h

+10 −5
Original line number Diff line number Diff line
@@ -318,16 +318,21 @@ struct ext4_new_group_data { 
 */

	/* Allocate any needed blocks and/or convert an unitialized

	   extent to be an initialized ext4 */

#define EXT4_GET_BLOCKS_CREATE			1

#define EXT4_GET_BLOCKS_CREATE			0x0001

	/* Request the creation of an unitialized extent */

#define EXT4_GET_BLOCKS_UNINIT_EXT		2

#define EXT4_GET_BLOCKS_UNINIT_EXT		0x0002

#define EXT4_GET_BLOCKS_CREATE_UNINIT_EXT	(EXT4_GET_BLOCKS_UNINIT_EXT|\

						 EXT4_GET_BLOCKS_CREATE)

	/* Update the ext4_inode_info i_disksize field */

#define EXT4_GET_BLOCKS_EXTEND_DISKSIZE		4

#define EXT4_GET_BLOCKS_EXTEND_DISKSIZE		0x0004

	/* Caller is from the delayed allocation writeout path,

	   so the filesystem blocks have already been accounted for */

#define EXT4_GET_BLOCKS_DELALLOC_RESERVE	8

	   so set the magic i_delalloc_reserve_flag after taking the 

	   inode allocation semaphore for */

#define EXT4_GET_BLOCKS_DELALLOC_RESERVE	0x0008

	/* Call ext4_da_update_reserve_space() after successfully 

	   allocating the blocks */

#define EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE	0x0010





/*

 * ioctl commands

fs/ext4/inode.c

+31 −25
Original line number Diff line number Diff line
@@ -1234,16 +1234,15 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block, 
		}

	}



	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {

	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)

		EXT4_I(inode)->i_delalloc_reserved_flag = 0;



	/*

		 * Update reserved blocks/metadata blocks

		 * after successful block allocation

		 * which were deferred till now

	 * Update reserved blocks/metadata blocks after successful

	 * block allocation which had been deferred till now.

	 */

		if ((retval > 0) && buffer_delay(bh))

	if ((retval > 0) && (flags & EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE))

		ext4_da_update_reserve_space(inode, retval);

	}



	up_write((&EXT4_I(inode)->i_data_sem));

	return retval;
@@ -2015,7 +2014,7 @@ static void ext4_print_free_blocks(struct inode *inode) 
 */

static int mpage_da_map_blocks(struct mpage_da_data *mpd)

{

	int err, blks;

	int err, blks, get_blocks_flags;

	struct buffer_head new;

	sector_t next = mpd->b_blocknr;

	unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
@@ -2040,23 +2039,30 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 
	BUG_ON(!handle);



	/*

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

	 * ext4_da_get_block_write(), since it calls ext4_get_blocks()

	 * with the EXT4_GET_BLOCKS_DELALLOC_RESERVE flag.  This flag

	 * causes ext4_get_blocks() 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(), 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_GET_BLOCKS_DELALLOC_RESERVE flag.

	 */

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

	blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks,

			       &new, EXT4_GET_BLOCKS_CREATE|

	 * Call ext4_get_blocks() to allocate any delayed allocation

	 * blocks, or to convert an uninitialized extent to be

	 * initialized (in the case where we have written into

	 * one or more preallocated blocks).

	 *

	 * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to

	 * indicate that we are on the delayed allocation path.  This

	 * affects functions in many different parts of the allocation

	 * call path.  This flag exists primarily because we don't

	 * want to change *many* call functions, so ext4_get_blocks()

	 * will set the magic i_delalloc_reserved_flag once the

	 * inode's allocation semaphore is taken.

	 *

	 * If the blocks in questions were delalloc blocks, set

	 * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting

	 * variables are updated after the blocks have been allocated.

	 */

	new.b_state = 0;

	get_blocks_flags = (EXT4_GET_BLOCKS_CREATE |

			    EXT4_GET_BLOCKS_DELALLOC_RESERVE);

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

		get_blocks_flags |= EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE;

	blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks,

			       &new, get_blocks_flags);

	if (blks < 0) {

		err = blks;

		/*