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Commit 6760bdcd authored by Bob Peterson's avatar Bob Peterson Committed by Steven Whitehouse
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[GFS2] Prevent infinite loop in try_rgrp_unlink() 



This is patch three of five for bug #248176.

The try_rgrp_unlink code in rgrp.c had an infinite loop.  This was
caused because the bitmap function rgblk_search can return a block
less than the "goal" block, in which case it was looping.  The fix is
to make it always march forward as needed.

Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 693ddeab

fs/gfs2/rgrp.c

+17 −13
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include "inode.h"



#define BFITNOENT ((u32)~0)

#define NO_BLOCK ((u64)~0)



/*

 * These routines are used by the resource group routines (rgrp.c)
@@ -116,8 +117,7 @@ static unsigned char gfs2_testbit(struct gfs2_rgrpd *rgd, unsigned char *buffer, 
 * @buffer: the buffer that holds the bitmaps

 * @buflen: the length (in bytes) of the buffer

 * @goal: start search at this block's bit-pair (within @buffer)

 * @old_state: GFS2_BLKST_XXX the state of the block we're looking for;

 *       bit 0 = alloc(1)/free(0), bit 1 = meta(1)/data(0)

 * @old_state: GFS2_BLKST_XXX the state of the block we're looking for.

 *

 * Scope of @goal and returned block number is only within this bitmap buffer,

 * not entire rgrp or filesystem.  @buffer will be offset from the actual
@@ -137,9 +137,13 @@ static u32 gfs2_bitfit(struct gfs2_rgrpd *rgd, unsigned char *buffer, 
	byte = buffer + (goal / GFS2_NBBY);

	bit = (goal % GFS2_NBBY) * GFS2_BIT_SIZE;

	end = buffer + buflen;

	alloc = (old_state & 1) ? 0 : 0x55;

	alloc = (old_state == GFS2_BLKST_FREE) ? 0x55 : 0;



	while (byte < end) {

		/* If we're looking for a free block we can eliminate all

		   bitmap settings with 0x55, which represents four data

		   blocks in a row.  If we're looking for a data block, we can

		   eliminate 0x00 which corresponds to four free blocks. */

		if ((*byte & 0x55) == alloc) {

			blk += (8 - bit) >> 1;
@@ -859,19 +863,21 @@ static int try_rgrp_fit(struct gfs2_rgrpd *rgd, struct gfs2_alloc *al) 
static struct inode *try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked)

{

	struct inode *inode;

	u32 goal = 0;

	u32 goal = 0, block;

	u64 no_addr;



	for(;;) {

		if (goal >= rgd->rd_data)

			break;

		goal = rgblk_search(rgd, goal, GFS2_BLKST_UNLINKED,

		block = rgblk_search(rgd, goal, GFS2_BLKST_UNLINKED,

				     GFS2_BLKST_UNLINKED);

		if (goal == BFITNOENT)

		if (block == BFITNOENT)

			break;

		no_addr = goal + rgd->rd_data0;

		/* rgblk_search can return a block < goal, so we need to

		   keep it marching forward. */

		no_addr = block + rgd->rd_data0;

		goal++;

		if (no_addr < *last_unlinked)

		if (*last_unlinked != NO_BLOCK && no_addr <= *last_unlinked)

			continue;

		*last_unlinked = no_addr;

		inode = gfs2_inode_lookup(rgd->rd_sbd->sd_vfs, DT_UNKNOWN,
@@ -1152,7 +1158,7 @@ int gfs2_inplace_reserve_i(struct gfs2_inode *ip, char *file, unsigned int line) 
	struct gfs2_alloc *al = &ip->i_alloc;

	struct inode *inode;

	int error = 0;

	u64 last_unlinked = 0;

	u64 last_unlinked = NO_BLOCK;



	if (gfs2_assert_warn(sdp, al->al_requested))

		return -EINVAL;
@@ -1305,9 +1311,7 @@ static u32 rgblk_search(struct gfs2_rgrpd *rgd, u32 goal, 
		goal = 0;

	}



	if (old_state != new_state) {

		gfs2_assert_withdraw(rgd->rd_sbd, blk != BFITNOENT);



	if (blk != BFITNOENT && old_state != new_state) {

		gfs2_trans_add_bh(rgd->rd_gl, bi->bi_bh, 1);

		gfs2_setbit(rgd, bi->bi_bh->b_data + bi->bi_offset,

			    bi->bi_len, blk, new_state);