Commit dffe12a8 authored by Bob Peterson's avatar Bob Peterson
Browse files

gfs2: Fix gfs2_testbit to use clone bitmaps 



Function gfs2_testbit is called in three places. Two of those places,
gfs2_alloc_extent and gfs2_unaligned_extlen, should be using the clone
bitmaps, not the "real" bitmaps. Function gfs2_unaligned_extlen is used
by the block reservations scheme to determine the length of an extent of
free blocks. Before this patch, it wasn't using the clone bitmap, which
means recently-freed blocks were treated as free blocks for the purposes
of an allocation.

This patch adds a new parameter to gfs2_testbit to indicate whether or
not the clone bitmaps should be used (if available).

Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
Reviewed-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 21e2156f

fs/gfs2/incore.h

+21 −0
Original line number Diff line number Diff line
@@ -65,6 +65,27 @@ struct gfs2_log_operations { 


#define GBF_FULL 1



/**

 * Clone bitmaps (bi_clone):

 *

 * - When a block is freed, we remember the previous state of the block in the

 *   clone bitmap, and only mark the block as free in the real bitmap.

 *

 * - When looking for a block to allocate, we check for a free block in the

 *   clone bitmap, and if no clone bitmap exists, in the real bitmap.

 *

 * - For allocating a block, we mark it as allocated in the real bitmap, and if

 *   a clone bitmap exists, also in the clone bitmap.

 *

 * - At the end of a log_flush, we copy the real bitmap into the clone bitmap

 *   to make the clone bitmap reflect the current allocation state.

 *   (Alternatively, we could remove the clone bitmap.)

 *

 * The clone bitmaps are in-core only, and is never written to disk.

 *

 * These steps ensure that blocks which have been freed in a transaction cannot

 * be reallocated in that same transaction.

 */

struct gfs2_bitmap {

	struct buffer_head *bi_bh;

	char *bi_clone;

fs/gfs2/rgrp.c

+19 −25
Original line number Diff line number Diff line
@@ -123,17 +123,26 @@ static inline void gfs2_setbit(const struct gfs2_rbm *rbm, bool do_clone, 
/**

 * gfs2_testbit - test a bit in the bitmaps

 * @rbm: The bit to test

 * @use_clone: If true, test the clone bitmap, not the official bitmap.

 *

 * Some callers like gfs2_unaligned_extlen need to test the clone bitmaps,

 * not the "real" bitmaps, to avoid allocating recently freed blocks.

 *

 * Returns: The two bit block state of the requested bit

 */



static inline u8 gfs2_testbit(const struct gfs2_rbm *rbm)

static inline u8 gfs2_testbit(const struct gfs2_rbm *rbm, bool use_clone)

{

	struct gfs2_bitmap *bi = rbm_bi(rbm);

	const u8 *buffer = bi->bi_bh->b_data + bi->bi_offset;

	const u8 *buffer;

	const u8 *byte;

	unsigned int bit;



	if (use_clone && bi->bi_clone)

		buffer = bi->bi_clone;

	else

		buffer = bi->bi_bh->b_data;

	buffer += bi->bi_offset;

	byte = buffer + (rbm->offset / GFS2_NBBY);

	bit = (rbm->offset % GFS2_NBBY) * GFS2_BIT_SIZE;
@@ -322,7 +331,7 @@ static bool gfs2_unaligned_extlen(struct gfs2_rbm *rbm, u32 n_unaligned, u32 *le 
	u8 res;



	for (n = 0; n < n_unaligned; n++) {

		res = gfs2_testbit(rbm);

		res = gfs2_testbit(rbm, true);

		if (res != GFS2_BLKST_FREE)

			return true;

		(*len)--;
@@ -2146,26 +2155,6 @@ void gfs2_inplace_release(struct gfs2_inode *ip) 
		gfs2_glock_dq_uninit(&rs->rs_rgd_gh);

}



/**

 * gfs2_get_block_type - Check a block in a RG is of given type

 * @rgd: the resource group holding the block

 * @block: the block number

 *

 * Returns: The block type (GFS2_BLKST_*)

 */



static unsigned char gfs2_get_block_type(struct gfs2_rgrpd *rgd, u64 block)

{

	struct gfs2_rbm rbm = { .rgd = rgd, };

	int ret;



	ret = gfs2_rbm_from_block(&rbm, block);

	WARN_ON_ONCE(ret != 0);



	return gfs2_testbit(&rbm);

}





/**

 * gfs2_alloc_extent - allocate an extent from a given bitmap

 * @rbm: the resource group information
@@ -2190,7 +2179,7 @@ static void gfs2_alloc_extent(const struct gfs2_rbm *rbm, bool dinode, 
	block++;

	while (*n < elen) {

		ret = gfs2_rbm_from_block(&pos, block);

		if (ret || gfs2_testbit(&pos) != GFS2_BLKST_FREE)

		if (ret || gfs2_testbit(&pos, true) != GFS2_BLKST_FREE)

			break;

		gfs2_trans_add_meta(pos.rgd->rd_gl, rbm_bi(&pos)->bi_bh);

		gfs2_setbit(&pos, true, GFS2_BLKST_USED);
@@ -2543,6 +2532,7 @@ int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type) 
{

	struct gfs2_rgrpd *rgd;

	struct gfs2_holder rgd_gh;

	struct gfs2_rbm rbm;

	int error = -EINVAL;



	rgd = gfs2_blk2rgrpd(sdp, no_addr, 1);
@@ -2553,7 +2543,11 @@ int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type) 
	if (error)

		goto fail;



	if (gfs2_get_block_type(rgd, no_addr) != type)

	rbm.rgd = rgd;

	error = gfs2_rbm_from_block(&rbm, no_addr);

	WARN_ON_ONCE(error != 0);



	if (gfs2_testbit(&rbm, false) != type)

		error = -ESTALE;



	gfs2_glock_dq_uninit(&rgd_gh);

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