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- Check the XLOCK before inspecting v_data.

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- Slightly rewrite the fsync loop to be more lock friendly.  We must
   acquire the vnode interlock before dropping the mnt lock.  We must
   also check XLOCK to prevent vclean() races.
 - Use LK_INTERLOCK in the vget() in ffs_sync to further prevent vclean()
   races.
 - Use a local variable to store the results of the nvp == TAILQ_NEXT
   test so that we do not access the vp after we've vrele()d it.
 - Add an XXX comment about UFS_UPDATE() not being protected by any lock
   here.  I suspect that it should need the VOP lock.
This commit is contained in:
jeff 2003-10-05 07:16:45 +00:00
parent d22d3e1bfb
commit 48e5ecf491
1 changed files with 25 additions and 9 deletions
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34
sys/ufs/ffs/ffs_vfsops.c
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@ -503,6 +503,10 @@ loop:
}
nvp = TAILQ_NEXT(vp, v_nmntvnodes);
VI_LOCK(vp);
if (vp->v_iflag & VI_XLOCK) {
VI_UNLOCK(vp);
continue;
}
mtx_unlock(&mntvnode_mtx);
/*
* Step 4: invalidate all inactive vnodes.
@ -1108,6 +1112,7 @@ ffs_sync(mp, waitfor, cred, td)
struct ufsmount *ump = VFSTOUFS(mp);
struct fs *fs;
int error, count, wait, lockreq, allerror = 0;
int restart;
fs = ump->um_fs;
if (fs->fs_fmod != 0 && fs->fs_ronly != 0) { /* XXX */
@ -1123,8 +1128,10 @@ ffs_sync(mp, waitfor, cred, td)
wait = 1;
lockreq = LK_EXCLUSIVE;
}
lockreq |= LK_INTERLOCK;
mtx_lock(&mntvnode_mtx);
loop:
restart = 0;
for (vp = TAILQ_FIRST(&mp->mnt_nvnodelist); vp != NULL; vp = nvp) {
/*
* If the vnode that we are about to sync is no longer
@ -1140,31 +1147,40 @@ loop:
* call unless there's a good chance that we have work to do.
*/
nvp = TAILQ_NEXT(vp, v_nmntvnodes);
VI_LOCK(vp);
if (vp->v_iflag & VI_XLOCK) {
VI_UNLOCK(vp);
continue;
}
ip = VTOI(vp);
if (vp->v_type == VNON || ((ip->i_flag &
(IN_ACCESS | IN_CHANGE | IN_MODIFIED | IN_UPDATE)) == 0 &&
TAILQ_EMPTY(&vp->v_dirtyblkhd))) {
VI_UNLOCK(vp);
continue;
}
mtx_unlock(&mntvnode_mtx);
if (vp->v_type != VCHR) {
mtx_unlock(&mntvnode_mtx);
if ((error = vget(vp, lockreq, td)) != 0) {
mtx_lock(&mntvnode_mtx);
if (error == ENOENT)
goto loop;
} else {
if ((error = VOP_FSYNC(vp, cred, waitfor, td)) != 0)
allerror = error;
VOP_UNLOCK(vp, 0, td);
vrele(vp);
mtx_lock(&mntvnode_mtx);
continue;
}
if ((error = VOP_FSYNC(vp, cred, waitfor, td)) != 0)
allerror = error;
VOP_UNLOCK(vp, 0, td);
mtx_lock(&mntvnode_mtx);
if (TAILQ_NEXT(vp, v_nmntvnodes) != nvp)
restart = 1;
vrele(vp);
} else {
mtx_unlock(&mntvnode_mtx);
VI_UNLOCK(vp);
/* XXX UFS_UPDATE is not protected by any lock. */
UFS_UPDATE(vp, wait);
mtx_lock(&mntvnode_mtx);
}
if (TAILQ_NEXT(vp, v_nmntvnodes) != nvp)
if (restart)
goto loop;
}
mtx_unlock(&mntvnode_mtx);