From 952043ac12a117d8e94bddd9088338d7ad20ca7d Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Thu, 23 Apr 2009 08:48:15 +0100 Subject: bitops: Add __ffs64 bitop Finds the first set bit in a 64 bit word. This is required in order to fix a bug in GFS2, but I think it should be a generic function in case of future users. Signed-off-by: Steven Whitehouse Reviewed-by: Christoph Lameter Reviewed-by: Willy Tarreau diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 6182913..c05a29c 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -112,6 +112,25 @@ static inline unsigned fls_long(unsigned long l) return fls64(l); } +/** + * __ffs64 - find first set bit in a 64 bit word + * @word: The 64 bit word + * + * On 64 bit arches this is a synomyn for __ffs + * The result is not defined if no bits are set, so check that @word + * is non-zero before calling this. + */ +static inline unsigned long __ffs64(u64 word) +{ +#if BITS_PER_LONG == 32 + if (((u32)word) == 0UL) + return __ffs((u32)(word >> 32)) + 32; +#elif BITS_PER_LONG != 64 +#error BITS_PER_LONG not 32 or 64 +#endif + return __ffs((unsigned long)word); +} + #ifdef __KERNEL__ #ifdef CONFIG_GENERIC_FIND_FIRST_BIT -- cgit v0.10.2 From d8bd504ab800c8e9aadb983914a33e7166320bec Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Thu, 23 Apr 2009 08:54:02 +0100 Subject: GFS2: Fix bug in block allocation The new bitfit algorithm was counting from the wrong end of 64 bit words in the bitfield. This fixes it by using __ffs64 instead of fls64 Signed-off-by: Steven Whitehouse diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index f03d024..c9786a4 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -212,8 +212,7 @@ static u32 gfs2_bitfit(const u8 *buf, const unsigned int len, if (tmp == 0) return BFITNOENT; ptr--; - bit = fls64(tmp); - bit--; /* fls64 always adds one to the bit count */ + bit = __ffs64(tmp); bit /= 2; /* two bits per entry in the bitmap */ return (((const unsigned char *)ptr - buf) * GFS2_NBBY) + bit; } -- cgit v0.10.2 From d9ba7615bfd8bb06f79c853f9dfff9e93a837941 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Thu, 23 Apr 2009 08:59:41 +0100 Subject: GFS2: Ensure that the inode goal block settings are updated GFS2 has a goal block associated with each inode indicating the search start position for future block allocations (in fact there are two, but thats for backward compatibility with GFS1 as they are set to identical locations in GFS2). In some circumstances, depending on the ordering of updates to the inode it was possible for the goal block settings to not be updated on disk. This patch ensures that the goal block will always get updated, thus reducing the potential for searching the same (already allocated) blocks again when looking for free space during block allocation. Signed-off-by: Steven Whitehouse diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index c9786a4..5650382 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -1444,10 +1444,12 @@ static struct gfs2_rgrpd *rgblk_free(struct gfs2_sbd *sdp, u64 bstart, u64 gfs2_alloc_block(struct gfs2_inode *ip, unsigned int *n) { struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode); + struct buffer_head *dibh; struct gfs2_alloc *al = ip->i_alloc; struct gfs2_rgrpd *rgd = al->al_rgd; u32 goal, blk; u64 block; + int error; if (rgrp_contains_block(rgd, ip->i_goal)) goal = ip->i_goal - rgd->rd_data0; @@ -1460,7 +1462,13 @@ u64 gfs2_alloc_block(struct gfs2_inode *ip, unsigned int *n) rgd->rd_last_alloc = blk; block = rgd->rd_data0 + blk; ip->i_goal = block; - + error = gfs2_meta_inode_buffer(ip, &dibh); + if (error == 0) { + struct gfs2_dinode *di = (struct gfs2_dinode *)dibh->b_data; + gfs2_trans_add_bh(ip->i_gl, dibh, 1); + di->di_goal_meta = di->di_goal_data = cpu_to_be64(ip->i_goal); + brelse(dibh); + } gfs2_assert_withdraw(sdp, rgd->rd_free >= *n); rgd->rd_free -= *n; -- cgit v0.10.2