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afs: Use fs_context to pass parameters over automount 

Alter the AFS automounting code to create and modify an fs_context struct
when parameterising a new mount triggered by an AFS mountpoint rather than
constructing device name and option strings.

Also remove the cell=, vol= and rwpath options as they are then redundant.
The reason they existed is because the 'device name' may be derived
literally from a mountpoint object in the filesystem, so default cell and
parent-type information needed to be passed in by some other method from
the automount routines.  The vol= option didn't end up being used.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Eric W. Biederman <ebiederm@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2018-11-01 23:07:27 +00:00 committed by Al Viro
parent 13fcc68370
commit c99c2171fc
3 changed files with 99 additions and 128 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/afs/internal.h
View File

@ -37,7 +37,6 @@ struct pagevec;
struct afs_call;
struct afs_fs_context {
bool rwpath; /* T if the parent should be considered R/W */
bool force; /* T to force cell type */
bool autocell; /* T if set auto mount operation */
bool dyn_root; /* T if dynamic root */

186
fs/afs/mntpt.c
View File

@ -48,6 +48,8 @@ static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
static const char afs_root_volume[] = "root.cell";
/*
* no valid lookup procedure on this sort of dir
*/
@ -68,109 +70,113 @@ static int afs_mntpt_open(struct inode *inode, struct file *file)
return -EREMOTE;
}
/*
* Set the parameters for the proposed superblock.
*/
static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
{
struct afs_fs_context *ctx = fc->fs_private;
struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
struct afs_cell *cell;
const char *p;
int ret;
if (fc->net_ns != src_as->net_ns) {
put_net(fc->net_ns);
fc->net_ns = get_net(src_as->net_ns);
}
if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
if (ctx->cell) {
afs_put_cell(ctx->net, ctx->cell);
ctx->cell = NULL;
}
if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
/* if the directory is a pseudo directory, use the d_name */
unsigned size = mntpt->d_name.len;
if (size < 2)
return -ENOENT;
p = mntpt->d_name.name;
if (mntpt->d_name.name[0] == '.') {
size--;
p++;
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
if (size > AFS_MAXCELLNAME)
return -ENAMETOOLONG;
cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
if (IS_ERR(cell)) {
pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
return PTR_ERR(cell);
}
ctx->cell = cell;
ctx->volname = afs_root_volume;
ctx->volnamesz = sizeof(afs_root_volume) - 1;
} else {
/* read the contents of the AFS special symlink */
struct page *page;
loff_t size = i_size_read(d_inode(mntpt));
char *buf;
if (src_as->cell)
ctx->cell = afs_get_cell(src_as->cell);
if (size > PAGE_SIZE - 1)
return -EINVAL;
page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
if (IS_ERR(page))
return PTR_ERR(page);
if (PageError(page)) {
ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
put_page(page);
return ret;
}
buf = kmap(page);
ret = vfs_parse_fs_string(fc, "source", buf, size);
kunmap(page);
put_page(page);
if (ret < 0)
return ret;
}
return 0;
}
/*
* create a vfsmount to be automounted
*/
static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
{
struct afs_super_info *as;
struct fs_context *fc;
struct vfsmount *mnt;
struct afs_vnode *vnode;
struct page *page;
char *devname, *options;
bool rwpath = false;
int ret;
_enter("{%pd}", mntpt);
BUG_ON(!d_inode(mntpt));
ret = -ENOMEM;
devname = (char *) get_zeroed_page(GFP_KERNEL);
if (!devname)
goto error_no_devname;
fc = fs_context_for_submount(&afs_fs_type, mntpt);
if (IS_ERR(fc))
return ERR_CAST(fc);
options = (char *) get_zeroed_page(GFP_KERNEL);
if (!options)
goto error_no_options;
ret = afs_mntpt_set_params(fc, mntpt);
if (!ret)
mnt = fc_mount(fc);
else
mnt = ERR_PTR(ret);
vnode = AFS_FS_I(d_inode(mntpt));
if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
/* if the directory is a pseudo directory, use the d_name */
static const char afs_root_cell[] = ":root.cell.";
unsigned size = mntpt->d_name.len;
ret = -ENOENT;
if (size < 2 || size > AFS_MAXCELLNAME)
goto error_no_page;
if (mntpt->d_name.name[0] == '.') {
devname[0] = '%';
memcpy(devname + 1, mntpt->d_name.name + 1, size - 1);
memcpy(devname + size, afs_root_cell,
sizeof(afs_root_cell));
rwpath = true;
} else {
devname[0] = '#';
memcpy(devname + 1, mntpt->d_name.name, size);
memcpy(devname + size + 1, afs_root_cell,
sizeof(afs_root_cell));
}
} else {
/* read the contents of the AFS special symlink */
loff_t size = i_size_read(d_inode(mntpt));
char *buf;
ret = -EINVAL;
if (size > PAGE_SIZE - 1)
goto error_no_page;
page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
if (IS_ERR(page)) {
ret = PTR_ERR(page);
goto error_no_page;
}
if (PageError(page)) {
ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
goto error;
}
buf = kmap_atomic(page);
memcpy(devname, buf, size);
kunmap_atomic(buf);
put_page(page);
page = NULL;
}
/* work out what options we want */
as = AFS_FS_S(mntpt->d_sb);
if (as->cell) {
memcpy(options, "cell=", 5);
strcpy(options + 5, as->cell->name);
if ((as->volume && as->volume->type == AFSVL_RWVOL) || rwpath)
strcat(options, ",rwpath");
}
/* try and do the mount */
_debug("--- attempting mount %s -o %s ---", devname, options);
mnt = vfs_submount(mntpt, &afs_fs_type, devname, options);
_debug("--- mount result %p ---", mnt);
free_page((unsigned long) devname);
free_page((unsigned long) options);
_leave(" = %p", mnt);
put_fs_context(fc);
return mnt;
error:
put_page(page);
error_no_page:
free_page((unsigned long) options);
error_no_options:
free_page((unsigned long) devname);
error_no_devname:
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*

40
fs/afs/super.c
View File

@ -66,20 +66,14 @@ static atomic_t afs_count_active_inodes;
enum afs_param {
Opt_autocell,
Opt_cell,
Opt_dyn,
Opt_rwpath,
Opt_source,
Opt_vol,
};
static const struct fs_parameter_spec afs_param_specs[] = {
fsparam_flag ("autocell", Opt_autocell),
fsparam_string("cell", Opt_cell),
fsparam_flag ("dyn", Opt_dyn),
fsparam_flag ("rwpath", Opt_rwpath),
fsparam_string("source", Opt_source),
fsparam_string("vol", Opt_vol),
{}
};
@ -202,8 +196,8 @@ static int afs_show_options(struct seq_file *m, struct dentry *root)
*
* This can be one of the following:
* "%[cell:]volume[.]" R/W volume
* "#[cell:]volume[.]" R/O or R/W volume (rwpath=0),
* or R/W (rwpath=1) volume
* "#[cell:]volume[.]" R/O or R/W volume (R/O parent),
* or R/W (R/W parent) volume
* "%[cell:]volume.readonly" R/O volume
* "#[cell:]volume.readonly" R/O volume
* "%[cell:]volume.backup" Backup volume
@ -234,9 +228,7 @@ static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param)
}
/* determine the type of volume we're looking for */
ctx->type = AFSVL_ROVOL;
ctx->force = false;
if (ctx->rwpath || name[0] == '%') {
if (name[0] == '%') {
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
@ -305,7 +297,6 @@ static int afs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct fs_parse_result result;
struct afs_fs_context *ctx = fc->fs_private;
struct afs_cell *cell;
int opt;
opt = fs_parse(fc, &afs_fs_parameters, param, &result);
@ -313,21 +304,6 @@ static int afs_parse_param(struct fs_context *fc, struct fs_parameter *param)
return opt;
switch (opt) {
case Opt_cell:
if (param->size <= 0)
return -EINVAL;
if (param->size > AFS_MAXCELLNAME)
return -ENAMETOOLONG;
rcu_read_lock();
cell = afs_lookup_cell_rcu(ctx->net, param->string, param->size);
rcu_read_unlock();
if (IS_ERR(cell))
return PTR_ERR(cell);
afs_put_cell(ctx->net, ctx->cell);
ctx->cell = cell;
break;
case Opt_source:
return afs_parse_source(fc, param);
@ -339,13 +315,6 @@ static int afs_parse_param(struct fs_context *fc, struct fs_parameter *param)
ctx->dyn_root = true;
break;
case Opt_rwpath:
ctx->rwpath = true;
break;
case Opt_vol:
return invalf(fc, "'vol' param is obsolete");
default:
return -EINVAL;
}
@ -616,9 +585,6 @@ static int afs_init_fs_context(struct fs_context *fc)
struct afs_fs_context *ctx;
struct afs_cell *cell;
if (current->nsproxy->net_ns != &init_net)
return -EINVAL;
ctx = kzalloc(sizeof(struct afs_fs_context), GFP_KERNEL);
if (!ctx)
return -ENOMEM;