From 6760bdcd03a12d7d082794311ccbaf44bfc23b06 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Tue, 24 Jul 2007 14:09:32 -0500 Subject: [PATCH] [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: Bob Peterson Signed-off-by: Steven Whitehouse --- fs/gfs2/rgrp.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index ce48c4594ec8..b93ac45b88bb 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -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, - GFS2_BLKST_UNLINKED); - if (goal == BFITNOENT) + block = rgblk_search(rgd, goal, GFS2_BLKST_UNLINKED, + GFS2_BLKST_UNLINKED); + 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);