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When renaming a directory from one parent directory to another,

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we need to call ufs_checkpath() to walk from our new location to
the root of the filesystem to ensure that we do not encounter
ourselves along the way. Until now, we accomplished this by reading
the ".." entries of each directory in our path until we reached
the root (or encountered an error). This change tries to avoid the
I/O of reading the ".." entries by first looking them up in the
name cache and only doing the I/O when the name cache lookup fails.

Reviewed by: kib
Tested by:   Peter Holm
MFC after:   4 weeks
This commit is contained in:
Kirk McKusick 2013-03-20 17:57:00 +00:00
parent a2c472e741
commit 3289d5877a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=248561
3 changed files with 54 additions and 17 deletions
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22
sys/kern/vfs_cache.c
View File

@ -1359,6 +1359,28 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
return (0);
}
struct vnode *
vn_dir_dd_ino(struct vnode *vp)
{
struct namecache *ncp;
struct vnode *ddvp;
ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
CACHE_RLOCK();
TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
continue;
ddvp = ncp->nc_dvp;
VI_LOCK(ddvp);
CACHE_RUNLOCK();
if (vget(ddvp, LK_INTERLOCK | LK_SHARED | LK_NOWAIT, curthread))
return (NULL);
return (ddvp);
}
CACHE_RUNLOCK();
return (NULL);
}
int
vn_commname(struct vnode *vp, char *buf, u_int buflen)
{

2
sys/sys/vnode.h
View File

@ -622,6 +622,8 @@ int vn_fullpath(struct thread *td, struct vnode *vn,
char **retbuf, char **freebuf);
int vn_fullpath_global(struct thread *td, struct vnode *vn,
char **retbuf, char **freebuf);
struct vnode *
vn_dir_dd_ino(struct vnode *vp);
int vn_commname(struct vnode *vn, char *buf, u_int buflen);
int vn_path_to_global_path(struct thread *td, struct vnode *vp,
char *path, u_int pathlen);

47
sys/ufs/ufs/ufs_lookup.c
View File

@ -1387,13 +1387,29 @@ ufs_dirempty(ip, parentino, cred)
}
static int
ufs_dir_dd_ino(struct vnode *vp, struct ucred *cred, ino_t *dd_ino)
ufs_dir_dd_ino(struct vnode *vp, struct ucred *cred, ino_t *dd_ino,
struct vnode **dd_vp)
{
struct dirtemplate dirbuf;
struct vnode *ddvp;
int error, namlen;
ASSERT_VOP_LOCKED(vp, "ufs_dir_dd_ino");
if (vp->v_type != VDIR)
return (ENOTDIR);
/*
* First check to see if we have it in the name cache.
*/
if ((ddvp = vn_dir_dd_ino(vp)) != NULL) {
KASSERT(ddvp->v_mount == vp->v_mount,
("ufs_dir_dd_ino: Unexpected mount point crossing"));
*dd_ino = VTOI(ddvp)->i_number;
*dd_vp = ddvp;
return (0);
}
/*
* Have to read the directory.
*/
error = vn_rdwr(UIO_READ, vp, (caddr_t)&dirbuf,
sizeof (struct dirtemplate), (off_t)0, UIO_SYSSPACE,
IO_NODELOCKED | IO_NOMACCHECK, cred, NOCRED, NULL, NULL);
@ -1411,6 +1427,7 @@ ufs_dir_dd_ino(struct vnode *vp, struct ucred *cred, ino_t *dd_ino)
dirbuf.dotdot_name[1] != '.')
return (ENOTDIR);
*dd_ino = dirbuf.dotdot_ino;
*dd_vp = NULL;
return (0);
}
@ -1435,7 +1452,7 @@ ufs_checkpath(ino_t source_ino, ino_t parent_ino, struct inode *target, struct u
if (target->i_number == ROOTINO)
return (0);
for (;;) {
error = ufs_dir_dd_ino(vp, cred, &dd_ino);
error = ufs_dir_dd_ino(vp, cred, &dd_ino, &vp1);
if (error != 0)
break;
if (dd_ino == source_ino) {
@ -1446,22 +1463,16 @@ ufs_checkpath(ino_t source_ino, ino_t parent_ino, struct inode *target, struct u
break;
if (dd_ino == parent_ino)
break;
error = VFS_VGET(mp, dd_ino, LK_SHARED | LK_NOWAIT, &vp1);
if (error != 0) {
*wait_ino = dd_ino;
break;
}
/* Recheck that ".." still points to vp1 after relock of vp */
error = ufs_dir_dd_ino(vp, cred, &dd_ino);
if (error != 0) {
vput(vp1);
break;
}
/* Redo the check of ".." if directory was reparented */
if (dd_ino != VTOI(vp1)->i_number) {
vput(vp1);
continue;
if (vp1 == NULL) {
error = VFS_VGET(mp, dd_ino, LK_SHARED | LK_NOWAIT,
&vp1);
if (error != 0) {
*wait_ino = dd_ino;
break;
}
}
KASSERT(dd_ino == VTOI(vp1)->i_number,
("directory %d reparented\n", VTOI(vp1)->i_number));
if (vp != tvp)
vput(vp);
vp = vp1;
@ -1469,6 +1480,8 @@ ufs_checkpath(ino_t source_ino, ino_t parent_ino, struct inode *target, struct u
if (error == ENOTDIR)
panic("checkpath: .. not a directory\n");
if (vp1 != NULL)
vput(vp1);
if (vp != tvp)
vput(vp);
return (error);