linux/fs/afs/mntpt.c

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/* mountpoint management
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/gfp.h>
#include "internal.h"
static struct dentry *afs_mntpt_lookup(struct inode *dir,
struct dentry *dentry,
struct nameidata *nd);
static int afs_mntpt_open(struct inode *inode, struct file *file);
static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
static void afs_mntpt_expiry_timed_out(struct work_struct *work);
const struct file_operations afs_mntpt_file_operations = {
.open = afs_mntpt_open,
};
const struct inode_operations afs_mntpt_inode_operations = {
.lookup = afs_mntpt_lookup,
.follow_link = afs_mntpt_follow_link,
.readlink = page_readlink,
.getattr = afs_getattr,
};
const struct inode_operations afs_autocell_inode_operations = {
.follow_link = afs_mntpt_follow_link,
.getattr = afs_getattr,
};
static LIST_HEAD(afs_vfsmounts);
static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
/*
* check a symbolic link to see whether it actually encodes a mountpoint
* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
*/
int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
{
struct page *page;
size_t size;
char *buf;
int ret;
_enter("{%x:%u,%u}",
vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
/* read the contents of the symlink into the pagecache */
page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
afs_page_filler, key);
if (IS_ERR(page)) {
ret = PTR_ERR(page);
goto out;
}
ret = -EIO;
if (PageError(page))
goto out_free;
buf = kmap(page);
/* examine the symlink's contents */
size = vnode->status.size;
_debug("symlink to %*.*s", (int) size, (int) size, buf);
if (size > 2 &&
(buf[0] == '%' || buf[0] == '#') &&
buf[size - 1] == '.'
) {
_debug("symlink is a mountpoint");
spin_lock(&vnode->lock);
set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
spin_unlock(&vnode->lock);
}
ret = 0;
kunmap(page);
out_free:
page_cache_release(page);
out:
_leave(" = %d", ret);
return ret;
}
/*
* no valid lookup procedure on this sort of dir
*/
static struct dentry *afs_mntpt_lookup(struct inode *dir,
struct dentry *dentry,
struct nameidata *nd)
{
_enter("%p,%p{%p{%s},%s}",
dir,
dentry,
dentry->d_parent,
dentry->d_parent ?
dentry->d_parent->d_name.name : (const unsigned char *) "",
dentry->d_name.name);
return ERR_PTR(-EREMOTE);
}
/*
* no valid open procedure on this sort of dir
*/
static int afs_mntpt_open(struct inode *inode, struct file *file)
{
_enter("%p,%p{%p{%s},%s}",
inode, file,
file->f_path.dentry->d_parent,
file->f_path.dentry->d_parent ?
file->f_path.dentry->d_parent->d_name.name :
(const unsigned char *) "",
file->f_path.dentry->d_name.name);
return -EREMOTE;
}
/*
* create a vfsmount to be automounted
*/
static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
{
struct afs_super_info *super;
struct vfsmount *mnt;
struct afs_vnode *vnode;
struct page *page;
char *devname, *options;
bool rwpath = false;
int ret;
_enter("{%s}", mntpt->d_name.name);
BUG_ON(!mntpt->d_inode);
ret = -ENOMEM;
devname = (char *) get_zeroed_page(GFP_KERNEL);
if (!devname)
goto error_no_devname;
options = (char *) get_zeroed_page(GFP_KERNEL);
if (!options)
goto error_no_options;
vnode = AFS_FS_I(mntpt->d_inode);
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, 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(mntpt->d_inode);
char *buf;
ret = -EINVAL;
if (size > PAGE_SIZE - 1)
goto error_no_page;
page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
if (IS_ERR(page)) {
ret = PTR_ERR(page);
goto error_no_page;
}
ret = -EIO;
if (PageError(page))
goto error;
buf = kmap_atomic(page, KM_USER0);
memcpy(devname, buf, size);
kunmap_atomic(buf, KM_USER0);
page_cache_release(page);
page = NULL;
}
/* work out what options we want */
super = AFS_FS_S(mntpt->d_sb);
memcpy(options, "cell=", 5);
strcpy(options + 5, super->volume->cell->name);
if (super->volume->type == AFSVL_RWVOL || rwpath)
strcat(options, ",rwpath");
/* try and do the mount */
_debug("--- attempting mount %s -o %s ---", devname, options);
mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
_debug("--- mount result %p ---", mnt);
free_page((unsigned long) devname);
free_page((unsigned long) options);
_leave(" = %p", mnt);
return mnt;
error:
page_cache_release(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);
}
/*
* follow a link from a mountpoint directory, thus causing it to be mounted
*/
static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct vfsmount *newmnt;
int err;
_enter("%p{%s},{%s:%p{%s},}",
dentry,
dentry->d_name.name,
nd->path.mnt->mnt_devname,
dentry,
nd->path.dentry->d_name.name);
dput(nd->path.dentry);
nd->path.dentry = dget(dentry);
newmnt = afs_mntpt_do_automount(nd->path.dentry);
if (IS_ERR(newmnt)) {
path_put(&nd->path);
return (void *)newmnt;
}
mntget(newmnt);
err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
switch (err) {
case 0:
path_put(&nd->path);
nd->path.mnt = newmnt;
nd->path.dentry = dget(newmnt->mnt_root);
schedule_delayed_work(&afs_mntpt_expiry_timer,
afs_mntpt_expiry_timeout * HZ);
break;
case -EBUSY:
/* someone else made a mount here whilst we were busy */
while (d_mountpoint(nd->path.dentry) &&
follow_down(&nd->path))
;
err = 0;
default:
mntput(newmnt);
break;
}
_leave(" = %d", err);
return ERR_PTR(err);
}
/*
* handle mountpoint expiry timer going off
*/
static void afs_mntpt_expiry_timed_out(struct work_struct *work)
{
_enter("");
if (!list_empty(&afs_vfsmounts)) {
mark_mounts_for_expiry(&afs_vfsmounts);
schedule_delayed_work(&afs_mntpt_expiry_timer,
afs_mntpt_expiry_timeout * HZ);
}
_leave("");
}
/*
* kill the AFS mountpoint timer if it's still running
*/
void afs_mntpt_kill_timer(void)
{
_enter("");
ASSERT(list_empty(&afs_vfsmounts));
cancel_delayed_work(&afs_mntpt_expiry_timer);
flush_scheduled_work();
}