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Add support for whiteouts on tmpfs.

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Right now unionfs only allows filesystems to be mounted on top of
another if it supports whiteouts. Even though I have sent a patch to
daichi@ to let unionfs work without it, we'd better also add support for
whiteouts to tmpfs.

This patch implements .vop_whiteout and makes necessary changes to
lookup() and readdir() to take them into account. We must also make sure
that when adding or removing a file, we honour the componentname's
DOWHITEOUT and ISWHITEOUT, to prevent duplicate filenames.

MFC after:	1 month
This commit is contained in:
Ed Schouten 2010-08-22 05:36:06 +00:00
parent 8024e98228
commit 99d57a6bd8
3 changed files with 109 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
sys/fs/tmpfs/tmpfs.h
View File

@ -72,7 +72,8 @@ struct tmpfs_dirent {
* td_namelen field must always be used when accessing its value. */
char * td_name;
/* Pointer to the node this entry refers to. */
/* Pointer to the node this entry refers to. In case this field
* is NULL, the node is a whiteout. */
struct tmpfs_node * td_node;
};
@ -434,6 +435,8 @@ int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
int tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *);
struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t);
int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *);
int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *);
void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *);
int tmpfs_reg_resize(struct vnode *, off_t);
int tmpfs_chflags(struct vnode *, int, struct ucred *, struct thread *);
int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);

94
sys/fs/tmpfs/tmpfs_subr.c
View File

@ -261,7 +261,8 @@ tmpfs_alloc_dirent(struct tmpfs_mount *tmp, struct tmpfs_node *node,
memcpy(nde->td_name, name, len);
nde->td_node = node;
node->tn_links++;
if (node != NULL)
node->tn_links++;
*de = nde;
@ -287,9 +288,10 @@ tmpfs_free_dirent(struct tmpfs_mount *tmp, struct tmpfs_dirent *de,
struct tmpfs_node *node;
node = de->td_node;
MPASS(node->tn_links > 0);
node->tn_links--;
if (node != NULL) {
MPASS(node->tn_links > 0);
node->tn_links--;
}
}
free(de->td_name, M_TMPFSNAME);
@ -518,6 +520,8 @@ tmpfs_alloc_file(struct vnode *dvp, struct vnode **vpp, struct vattr *vap,
/* Now that all required items are allocated, we can proceed to
* insert the new node into the directory, an operation that
* cannot fail. */
if (cnp->cn_flags & ISWHITEOUT)
tmpfs_dir_whiteout_remove(dvp, cnp);
tmpfs_dir_attach(dvp, de);
out:
@ -768,39 +772,44 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, off_t *cntp)
/* Create a dirent structure representing the current
* tmpfs_node and fill it. */
d.d_fileno = de->td_node->tn_id;
switch (de->td_node->tn_type) {
case VBLK:
d.d_type = DT_BLK;
break;
if (de->td_node == NULL) {
d.d_fileno = 1;
d.d_type = DT_WHT;
} else {
d.d_fileno = de->td_node->tn_id;
switch (de->td_node->tn_type) {
case VBLK:
d.d_type = DT_BLK;
break;
case VCHR:
d.d_type = DT_CHR;
break;
case VCHR:
d.d_type = DT_CHR;
break;
case VDIR:
d.d_type = DT_DIR;
break;
case VDIR:
d.d_type = DT_DIR;
break;
case VFIFO:
d.d_type = DT_FIFO;
break;
case VFIFO:
d.d_type = DT_FIFO;
break;
case VLNK:
d.d_type = DT_LNK;
break;
case VLNK:
d.d_type = DT_LNK;
break;
case VREG:
d.d_type = DT_REG;
break;
case VREG:
d.d_type = DT_REG;
break;
case VSOCK:
d.d_type = DT_SOCK;
break;
case VSOCK:
d.d_type = DT_SOCK;
break;
default:
panic("tmpfs_dir_getdents: type %p %d",
de->td_node, (int)de->td_node->tn_type);
default:
panic("tmpfs_dir_getdents: type %p %d",
de->td_node, (int)de->td_node->tn_type);
}
}
d.d_namlen = de->td_namelen;
MPASS(de->td_namelen < sizeof(d.d_name));
@ -837,6 +846,31 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, off_t *cntp)
return error;
}
int
tmpfs_dir_whiteout_add(struct vnode *dvp, struct componentname *cnp)
{
struct tmpfs_dirent *de;
int error;
error = tmpfs_alloc_dirent(VFS_TO_TMPFS(dvp->v_mount), NULL,
cnp->cn_nameptr, cnp->cn_namelen, &de);
if (error != 0)
return (error);
tmpfs_dir_attach(dvp, de);
return (0);
}
void
tmpfs_dir_whiteout_remove(struct vnode *dvp, struct componentname *cnp)
{
struct tmpfs_dirent *de;
de = tmpfs_dir_lookup(VP_TO_TMPFS_DIR(dvp), NULL, cnp);
MPASS(de != NULL && de->td_node == NULL);
tmpfs_dir_detach(dvp, de);
tmpfs_free_dirent(VFS_TO_TMPFS(dvp->v_mount), de, TRUE);
}
/* --------------------------------------------------------------------- */
/*

43
sys/fs/tmpfs/tmpfs_vnops.c
View File

@ -109,14 +109,19 @@ tmpfs_lookup(struct vop_cachedlookup_args *v)
error = 0;
} else {
de = tmpfs_dir_lookup(dnode, NULL, cnp);
if (de == NULL) {
if (de != NULL && de->td_node == NULL)
cnp->cn_flags |= ISWHITEOUT;
if (de == NULL || de->td_node == NULL) {
/* The entry was not found in the directory.
* This is OK if we are creating or renaming an
* entry and are working on the last component of
* the path name. */
if ((cnp->cn_flags & ISLASTCN) &&
(cnp->cn_nameiop == CREATE || \
cnp->cn_nameiop == RENAME)) {
cnp->cn_nameiop == RENAME ||
(cnp->cn_nameiop == DELETE &&
cnp->cn_flags & DOWHITEOUT &&
cnp->cn_flags & ISWHITEOUT))) {
error = VOP_ACCESS(dvp, VWRITE, cnp->cn_cred,
cnp->cn_thread);
if (error != 0)
@ -834,6 +839,8 @@ tmpfs_remove(struct vop_remove_args *v)
/* Remove the entry from the directory; as it is a file, we do not
* have to change the number of hard links of the directory. */
tmpfs_dir_detach(dvp, de);
if (v->a_cnp->cn_flags & DOWHITEOUT)
tmpfs_dir_whiteout_add(dvp, v->a_cnp);
/* Free the directory entry we just deleted. Note that the node
* referred by it will not be removed until the vnode is really
@ -904,6 +911,8 @@ tmpfs_link(struct vop_link_args *v)
goto out;
/* Insert the new directory entry into the appropriate directory. */
if (cnp->cn_flags & ISWHITEOUT)
tmpfs_dir_whiteout_remove(dvp, cnp);
tmpfs_dir_attach(dvp, de);
/* vp link count has changed, so update node times. */
@ -1099,6 +1108,10 @@ tmpfs_rename(struct vop_rename_args *v)
/* Do the move: just remove the entry from the source directory
* and insert it into the target one. */
tmpfs_dir_detach(fdvp, de);
if (fcnp->cn_flags & DOWHITEOUT)
tmpfs_dir_whiteout_add(fdvp, fcnp);
if (tcnp->cn_flags & ISWHITEOUT)
tmpfs_dir_whiteout_remove(tdvp, tcnp);
tmpfs_dir_attach(tdvp, de);
}
@ -1223,6 +1236,8 @@ tmpfs_rmdir(struct vop_rmdir_args *v)
/* Detach the directory entry from the directory (dnode). */
tmpfs_dir_detach(dvp, de);
if (v->a_cnp->cn_flags & DOWHITEOUT)
tmpfs_dir_whiteout_add(dvp, v->a_cnp);
/* No vnode should be allocated for this entry from this point */
TMPFS_NODE_LOCK(node);
@ -1541,6 +1556,29 @@ tmpfs_vptofh(struct vop_vptofh_args *ap)
return (0);
}
static int
tmpfs_whiteout(struct vop_whiteout_args *ap)
{
struct vnode *dvp = ap->a_dvp;
struct componentname *cnp = ap->a_cnp;
struct tmpfs_dirent *de;
switch (ap->a_flags) {
case LOOKUP:
return (0);
case CREATE:
de = tmpfs_dir_lookup(VP_TO_TMPFS_DIR(dvp), NULL, cnp);
if (de != NULL)
return (de->td_node == NULL ? 0 : EEXIST);
return (tmpfs_dir_whiteout_add(dvp, cnp));
case DELETE:
tmpfs_dir_whiteout_remove(dvp, cnp);
return (0);
default:
panic("tmpfs_whiteout: unknown op");
}
}
/* --------------------------------------------------------------------- */
/*
@ -1573,6 +1611,7 @@ struct vop_vector tmpfs_vnodeop_entries = {
.vop_print = tmpfs_print,
.vop_pathconf = tmpfs_pathconf,
.vop_vptofh = tmpfs_vptofh,
.vop_whiteout = tmpfs_whiteout,
.vop_bmap = VOP_EOPNOTSUPP,
};