From 7839b23f008a108df149b2f2d12db6240cc8ead8 Mon Sep 17 00:00:00 2001 From: Kirk McKusick Date: Sat, 16 Feb 2013 15:11:40 +0000 Subject: [PATCH] The UFS2 filesystem allocates new blocks of inodes as they are needed. When a cylinder group runs short of inodes, a new block for inodes is allocated, zero'ed, and written to the disk. The zero'ed inodes must be on the disk before the cylinder group can be updated to claim them. If the cylinder group claiming the new inodes were written before the zero'ed block of inodes, the system could crash with the filesystem in an unrecoverable state. Rather than adding a soft updates dependency to ensure that the new inode block is written before it is claimed by the cylinder group map, we just do a barrier write of the zero'ed inode block to ensure that it will get written before the updated cylinder group map can be written. This change should only slow down bulk loading of newly created filesystems since that is the primary time that new inode blocks need to be created. Reported by: Robert Watson Reviewed by: kib Tested by: Peter Holm --- sys/ufs/ffs/ffs_alloc.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/sys/ufs/ffs/ffs_alloc.c b/sys/ufs/ffs/ffs_alloc.c index d462cbb1b26..abe4073f16b 100644 --- a/sys/ufs/ffs/ffs_alloc.c +++ b/sys/ufs/ffs/ffs_alloc.c @@ -1861,7 +1861,6 @@ gotit: /* * Check to see if we need to initialize more inodes. */ - ibp = NULL; if (fs->fs_magic == FS_UFS2_MAGIC && ipref + INOPB(fs) > cgp->cg_initediblk && cgp->cg_initediblk < cgp->cg_niblk) { @@ -1874,6 +1873,16 @@ gotit: dp2->di_gen = arc4random() / 2 + 1; dp2++; } + /* + * Rather than adding a soft updates dependency to ensure + * that the new inode block is written before it is claimed + * by the cylinder group map, we just do a barrier write + * here. The barrier write will ensure that the inode block + * gets written before the updated cylinder group map can be + * written. The barrier write should only slow down bulk + * loading of newly created filesystems. + */ + babarrierwrite(ibp); cgp->cg_initediblk += INOPB(fs); } UFS_LOCK(ump); @@ -1892,8 +1901,6 @@ gotit: if (DOINGSOFTDEP(ITOV(ip))) softdep_setup_inomapdep(bp, ip, cg * fs->fs_ipg + ipref, mode); bdwrite(bp); - if (ibp != NULL) - bawrite(ibp); return ((ino_t)(cg * fs->fs_ipg + ipref)); }