linux-sg2042/fs/hostfs/hostfs_kern.c

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/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*
* Ported the filesystem routines to 2.5.
* 2003-02-10 Petr Baudis <pasky@ucw.cz>
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/statfs.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 16:04:11 +08:00
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include "hostfs.h"
#include "init.h"
#include "kern.h"
struct hostfs_inode_info {
char *host_filename;
int fd;
fmode_t mode;
struct inode vfs_inode;
};
static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
{
return list_entry(inode, struct hostfs_inode_info, vfs_inode);
}
#define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
static int hostfs_d_delete(struct dentry *dentry)
{
return 1;
}
static const struct dentry_operations hostfs_dentry_ops = {
.d_delete = hostfs_d_delete,
};
/* Changed in hostfs_args before the kernel starts running */
static char *root_ino = "";
static int append = 0;
#define HOSTFS_SUPER_MAGIC 0x00c0ffee
static const struct inode_operations hostfs_iops;
static const struct inode_operations hostfs_dir_iops;
static const struct address_space_operations hostfs_link_aops;
#ifndef MODULE
static int __init hostfs_args(char *options, int *add)
{
char *ptr;
ptr = strchr(options, ',');
if (ptr != NULL)
*ptr++ = '\0';
if (*options != '\0')
root_ino = options;
options = ptr;
while (options) {
ptr = strchr(options, ',');
if (ptr != NULL)
*ptr++ = '\0';
if (*options != '\0') {
if (!strcmp(options, "append"))
append = 1;
else printf("hostfs_args - unsupported option - %s\n",
options);
}
options = ptr;
}
return 0;
}
__uml_setup("hostfs=", hostfs_args,
"hostfs=<root dir>,<flags>,...\n"
" This is used to set hostfs parameters. The root directory argument\n"
" is used to confine all hostfs mounts to within the specified directory\n"
" tree on the host. If this isn't specified, then a user inside UML can\n"
" mount anything on the host that's accessible to the user that's running\n"
" it.\n"
" The only flag currently supported is 'append', which specifies that all\n"
" files opened by hostfs will be opened in append mode.\n\n"
);
#endif
static char *dentry_name(struct dentry *dentry, int extra)
{
struct dentry *parent;
char *root, *name;
int len;
len = 0;
parent = dentry;
while (parent->d_parent != parent) {
len += parent->d_name.len + 1;
parent = parent->d_parent;
}
root = HOSTFS_I(parent->d_inode)->host_filename;
len += strlen(root);
name = kmalloc(len + extra + 1, GFP_KERNEL);
if (name == NULL)
return NULL;
name[len] = '\0';
parent = dentry;
while (parent->d_parent != parent) {
len -= parent->d_name.len + 1;
name[len] = '/';
strncpy(&name[len + 1], parent->d_name.name,
parent->d_name.len);
parent = parent->d_parent;
}
strncpy(name, root, strlen(root));
return name;
}
static char *inode_name(struct inode *ino, int extra)
{
struct dentry *dentry;
dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
return dentry_name(dentry, extra);
}
static int read_name(struct inode *ino, char *name)
{
/*
* The non-int inode fields are copied into ints by stat_file and
* then copied into the inode because passing the actual pointers
* in and having them treated as int * breaks on big-endian machines
*/
int err;
int i_mode, i_nlink, i_blksize;
unsigned long long i_size;
unsigned long long i_ino;
unsigned long long i_blocks;
err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
&ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
&ino->i_ctime, &i_blksize, &i_blocks, -1);
if (err)
return err;
ino->i_ino = i_ino;
ino->i_mode = i_mode;
ino->i_nlink = i_nlink;
ino->i_size = i_size;
ino->i_blocks = i_blocks;
return 0;
}
static char *follow_link(char *link)
{
int len, n;
char *name, *resolved, *end;
len = 64;
while (1) {
n = -ENOMEM;
name = kmalloc(len, GFP_KERNEL);
if (name == NULL)
goto out;
n = hostfs_do_readlink(link, name, len);
if (n < len)
break;
len *= 2;
kfree(name);
}
if (n < 0)
goto out_free;
if (*name == '/')
return name;
end = strrchr(link, '/');
if (end == NULL)
return name;
*(end + 1) = '\0';
len = strlen(link) + strlen(name) + 1;
resolved = kmalloc(len, GFP_KERNEL);
if (resolved == NULL) {
n = -ENOMEM;
goto out_free;
}
sprintf(resolved, "%s%s", link, name);
kfree(name);
kfree(link);
return resolved;
out_free:
kfree(name);
out:
return ERR_PTR(n);
}
static int hostfs_read_inode(struct inode *ino)
{
char *name;
int err = 0;
/*
* Unfortunately, we are called from iget() when we don't have a dentry
* allocated yet.
*/
if (list_empty(&ino->i_dentry))
goto out;
err = -ENOMEM;
name = inode_name(ino, 0);
if (name == NULL)
goto out;
if (file_type(name, NULL, NULL) == OS_TYPE_SYMLINK) {
name = follow_link(name);
if (IS_ERR(name)) {
err = PTR_ERR(name);
goto out;
}
}
err = read_name(ino, name);
kfree(name);
out:
return err;
}
static struct inode *hostfs_iget(struct super_block *sb)
{
struct inode *inode;
long ret;
inode = iget_locked(sb, 0);
if (!inode)
return ERR_PTR(-ENOMEM);
if (inode->i_state & I_NEW) {
ret = hostfs_read_inode(inode);
if (ret < 0) {
iget_failed(inode);
return ERR_PTR(ret);
}
unlock_new_inode(inode);
}
return inode;
}
int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
{
/*
* do_statfs uses struct statfs64 internally, but the linux kernel
* struct statfs still has 32-bit versions for most of these fields,
* so we convert them here
*/
int err;
long long f_blocks;
long long f_bfree;
long long f_bavail;
long long f_files;
long long f_ffree;
err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename,
&sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
&f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
&sf->f_namelen, sf->f_spare);
if (err)
return err;
sf->f_blocks = f_blocks;
sf->f_bfree = f_bfree;
sf->f_bavail = f_bavail;
sf->f_files = f_files;
sf->f_ffree = f_ffree;
sf->f_type = HOSTFS_SUPER_MAGIC;
return 0;
}
static struct inode *hostfs_alloc_inode(struct super_block *sb)
{
struct hostfs_inode_info *hi;
hi = kmalloc(sizeof(*hi), GFP_KERNEL);
if (hi == NULL)
return NULL;
*hi = ((struct hostfs_inode_info) { .host_filename = NULL,
.fd = -1,
.mode = 0 });
inode_init_once(&hi->vfs_inode);
return &hi->vfs_inode;
}
static void hostfs_delete_inode(struct inode *inode)
{
truncate_inode_pages(&inode->i_data, 0);
if (HOSTFS_I(inode)->fd != -1) {
close_file(&HOSTFS_I(inode)->fd);
HOSTFS_I(inode)->fd = -1;
}
clear_inode(inode);
}
static void hostfs_destroy_inode(struct inode *inode)
{
kfree(HOSTFS_I(inode)->host_filename);
/*
* XXX: This should not happen, probably. The check is here for
* additional safety.
*/
if (HOSTFS_I(inode)->fd != -1) {
close_file(&HOSTFS_I(inode)->fd);
printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
}
kfree(HOSTFS_I(inode));
}
static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
struct inode *root = vfs->mnt_sb->s_root->d_inode;
const char *root_path = HOSTFS_I(root)->host_filename;
size_t offset = strlen(root_ino) + 1;
if (strlen(root_path) > offset)
seq_printf(seq, ",%s", root_path + offset);
return 0;
}
static const struct super_operations hostfs_sbops = {
.alloc_inode = hostfs_alloc_inode,
.drop_inode = generic_delete_inode,
.delete_inode = hostfs_delete_inode,
.destroy_inode = hostfs_destroy_inode,
.statfs = hostfs_statfs,
.show_options = hostfs_show_options,
};
int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
{
void *dir;
char *name;
unsigned long long next, ino;
int error, len;
name = dentry_name(file->f_path.dentry, 0);
if (name == NULL)
return -ENOMEM;
dir = open_dir(name, &error);
kfree(name);
if (dir == NULL)
return -error;
next = file->f_pos;
while ((name = read_dir(dir, &next, &ino, &len)) != NULL) {
error = (*filldir)(ent, name, len, file->f_pos,
ino, DT_UNKNOWN);
if (error) break;
file->f_pos = next;
}
close_dir(dir);
return 0;
}
int hostfs_file_open(struct inode *ino, struct file *file)
{
char *name;
fmode_t mode = 0;
int r = 0, w = 0, fd;
mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
if ((mode & HOSTFS_I(ino)->mode) == mode)
return 0;
/*
* The file may already have been opened, but with the wrong access,
* so this resets things and reopens the file with the new access.
*/
if (HOSTFS_I(ino)->fd != -1) {
close_file(&HOSTFS_I(ino)->fd);
HOSTFS_I(ino)->fd = -1;
}
HOSTFS_I(ino)->mode |= mode;
if (HOSTFS_I(ino)->mode & FMODE_READ)
r = 1;
if (HOSTFS_I(ino)->mode & FMODE_WRITE)
w = 1;
if (w)
r = 1;
name = dentry_name(file->f_path.dentry, 0);
if (name == NULL)
return -ENOMEM;
fd = open_file(name, r, w, append);
kfree(name);
if (fd < 0)
return fd;
FILE_HOSTFS_I(file)->fd = fd;
return 0;
}
int hostfs_fsync(struct file *file, int datasync)
{
return fsync_file(HOSTFS_I(file->f_mapping->host)->fd, datasync);
}
static const struct file_operations hostfs_file_fops = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.splice_read = generic_file_splice_read,
.aio_read = generic_file_aio_read,
.aio_write = generic_file_aio_write,
.write = do_sync_write,
.mmap = generic_file_mmap,
.open = hostfs_file_open,
.release = NULL,
.fsync = hostfs_fsync,
};
static const struct file_operations hostfs_dir_fops = {
.llseek = generic_file_llseek,
.readdir = hostfs_readdir,
.read = generic_read_dir,
};
int hostfs_writepage(struct page *page, struct writeback_control *wbc)
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
char *buffer;
unsigned long long base;
int count = PAGE_CACHE_SIZE;
int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
int err;
if (page->index >= end_index)
count = inode->i_size & (PAGE_CACHE_SIZE-1);
buffer = kmap(page);
base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
if (err != count) {
ClearPageUptodate(page);
goto out;
}
if (base > inode->i_size)
inode->i_size = base;
if (PageError(page))
ClearPageError(page);
err = 0;
out:
kunmap(page);
unlock_page(page);
return err;
}
int hostfs_readpage(struct file *file, struct page *page)
{
char *buffer;
long long start;
int err = 0;
start = (long long) page->index << PAGE_CACHE_SHIFT;
buffer = kmap(page);
err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
PAGE_CACHE_SIZE);
if (err < 0)
goto out;
memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
flush_dcache_page(page);
SetPageUptodate(page);
if (PageError(page)) ClearPageError(page);
err = 0;
out:
kunmap(page);
unlock_page(page);
return err;
}
int hostfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
fs: symlink write_begin allocation context fix With the write_begin/write_end aops, page_symlink was broken because it could no longer pass a GFP_NOFS type mask into the point where the allocations happened. They are done in write_begin, which would always assume that the filesystem can be entered from reclaim. This bug could cause filesystem deadlocks. The funny thing with having a gfp_t mask there is that it doesn't really allow the caller to arbitrarily tinker with the context in which it can be called. It couldn't ever be GFP_ATOMIC, for example, because it needs to take the page lock. The only thing any callers care about is __GFP_FS anyway, so turn that into a single flag. Add a new flag for write_begin, AOP_FLAG_NOFS. Filesystems can now act on this flag in their write_begin function. Change __grab_cache_page to accept a nofs argument as well, to honour that flag (while we're there, change the name to grab_cache_page_write_begin which is more instructive and does away with random leading underscores). This is really a more flexible way to go in the end anyway -- if a filesystem happens to want any extra allocations aside from the pagecache ones in ints write_begin function, it may now use GFP_KERNEL (rather than GFP_NOFS) for common case allocations (eg. ocfs2_alloc_write_ctxt, for a random example). [kosaki.motohiro@jp.fujitsu.com: fix ubifs] [kosaki.motohiro@jp.fujitsu.com: fix fuse] Signed-off-by: Nick Piggin <npiggin@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <stable@kernel.org> [2.6.28.x] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Cleaned up the calling convention: just pass in the AOP flags untouched to the grab_cache_page_write_begin() function. That just simplifies everybody, and may even allow future expansion of the logic. - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-05 04:00:53 +08:00
*pagep = grab_cache_page_write_begin(mapping, index, flags);
if (!*pagep)
return -ENOMEM;
return 0;
}
int hostfs_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
struct inode *inode = mapping->host;
void *buffer;
unsigned from = pos & (PAGE_CACHE_SIZE - 1);
int err;
buffer = kmap(page);
err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
kunmap(page);
if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
SetPageUptodate(page);
/*
* If err > 0, write_file has added err to pos, so we are comparing
* i_size against the last byte written.
*/
if (err > 0 && (pos > inode->i_size))
inode->i_size = pos;
unlock_page(page);
page_cache_release(page);
return err;
}
static const struct address_space_operations hostfs_aops = {
.writepage = hostfs_writepage,
.readpage = hostfs_readpage,
.set_page_dirty = __set_page_dirty_nobuffers,
.write_begin = hostfs_write_begin,
.write_end = hostfs_write_end,
};
static int init_inode(struct inode *inode, struct dentry *dentry)
{
char *name;
int type, err = -ENOMEM;
int maj, min;
dev_t rdev = 0;
if (dentry) {
name = dentry_name(dentry, 0);
if (name == NULL)
goto out;
type = file_type(name, &maj, &min);
/* Reencode maj and min with the kernel encoding.*/
rdev = MKDEV(maj, min);
kfree(name);
}
else type = OS_TYPE_DIR;
err = 0;
if (type == OS_TYPE_SYMLINK)
inode->i_op = &page_symlink_inode_operations;
else if (type == OS_TYPE_DIR)
inode->i_op = &hostfs_dir_iops;
else inode->i_op = &hostfs_iops;
if (type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
else inode->i_fop = &hostfs_file_fops;
if (type == OS_TYPE_SYMLINK)
inode->i_mapping->a_ops = &hostfs_link_aops;
else inode->i_mapping->a_ops = &hostfs_aops;
switch (type) {
case OS_TYPE_CHARDEV:
init_special_inode(inode, S_IFCHR, rdev);
break;
case OS_TYPE_BLOCKDEV:
init_special_inode(inode, S_IFBLK, rdev);
break;
case OS_TYPE_FIFO:
init_special_inode(inode, S_IFIFO, 0);
break;
case OS_TYPE_SOCK:
init_special_inode(inode, S_IFSOCK, 0);
break;
}
out:
return err;
}
int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
struct nameidata *nd)
{
struct inode *inode;
char *name;
int error, fd;
inode = hostfs_iget(dir->i_sb);
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
goto out;
}
error = init_inode(inode, dentry);
if (error)
goto out_put;
error = -ENOMEM;
name = dentry_name(dentry, 0);
if (name == NULL)
goto out_put;
fd = file_create(name,
mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
if (fd < 0)
error = fd;
else error = read_name(inode, name);
kfree(name);
if (error)
goto out_put;
HOSTFS_I(inode)->fd = fd;
HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
d_instantiate(dentry, inode);
return 0;
out_put:
iput(inode);
out:
return error;
}
struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
struct nameidata *nd)
{
struct inode *inode;
char *name;
int err;
inode = hostfs_iget(ino->i_sb);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out;
}
err = init_inode(inode, dentry);
if (err)
goto out_put;
err = -ENOMEM;
name = dentry_name(dentry, 0);
if (name == NULL)
goto out_put;
err = read_name(inode, name);
kfree(name);
if (err == -ENOENT) {
iput(inode);
inode = NULL;
}
else if (err)
goto out_put;
d_add(dentry, inode);
dentry->d_op = &hostfs_dentry_ops;
return NULL;
out_put:
iput(inode);
out:
return ERR_PTR(err);
}
static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
{
char *file;
int len;
file = inode_name(ino, dentry->d_name.len + 1);
if (file == NULL)
return NULL;
strcat(file, "/");
len = strlen(file);
strncat(file, dentry->d_name.name, dentry->d_name.len);
file[len + dentry->d_name.len] = '\0';
return file;
}
int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
{
char *from_name, *to_name;
int err;
if ((from_name = inode_dentry_name(ino, from)) == NULL)
return -ENOMEM;
to_name = dentry_name(to, 0);
if (to_name == NULL) {
kfree(from_name);
return -ENOMEM;
}
err = link_file(to_name, from_name);
kfree(from_name);
kfree(to_name);
return err;
}
int hostfs_unlink(struct inode *ino, struct dentry *dentry)
{
char *file;
int err;
if ((file = inode_dentry_name(ino, dentry)) == NULL)
return -ENOMEM;
if (append)
return -EPERM;
err = unlink_file(file);
kfree(file);
return err;
}
int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
{
char *file;
int err;
if ((file = inode_dentry_name(ino, dentry)) == NULL)
return -ENOMEM;
err = make_symlink(file, to);
kfree(file);
return err;
}
int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
{
char *file;
int err;
if ((file = inode_dentry_name(ino, dentry)) == NULL)
return -ENOMEM;
err = do_mkdir(file, mode);
kfree(file);
return err;
}
int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
{
char *file;
int err;
if ((file = inode_dentry_name(ino, dentry)) == NULL)
return -ENOMEM;
err = do_rmdir(file);
kfree(file);
return err;
}
int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
struct inode *inode;
char *name;
int err;
inode = hostfs_iget(dir->i_sb);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out;
}
err = init_inode(inode, dentry);
if (err)
goto out_put;
err = -ENOMEM;
name = dentry_name(dentry, 0);
if (name == NULL)
goto out_put;
init_special_inode(inode, mode, dev);
err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
if (err)
goto out_free;
err = read_name(inode, name);
kfree(name);
if (err)
goto out_put;
d_instantiate(dentry, inode);
return 0;
out_free:
kfree(name);
out_put:
iput(inode);
out:
return err;
}
int hostfs_rename(struct inode *from_ino, struct dentry *from,
struct inode *to_ino, struct dentry *to)
{
char *from_name, *to_name;
int err;
if ((from_name = inode_dentry_name(from_ino, from)) == NULL)
return -ENOMEM;
if ((to_name = inode_dentry_name(to_ino, to)) == NULL) {
kfree(from_name);
return -ENOMEM;
}
err = rename_file(from_name, to_name);
kfree(from_name);
kfree(to_name);
return err;
}
int hostfs_permission(struct inode *ino, int desired)
{
char *name;
int r = 0, w = 0, x = 0, err;
if (desired & MAY_READ) r = 1;
if (desired & MAY_WRITE) w = 1;
if (desired & MAY_EXEC) x = 1;
name = inode_name(ino, 0);
if (name == NULL)
return -ENOMEM;
if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
err = 0;
else
err = access_file(name, r, w, x);
kfree(name);
if (!err)
err = generic_permission(ino, desired, NULL);
return err;
}
int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct hostfs_iattr attrs;
char *name;
int err;
int fd = HOSTFS_I(dentry->d_inode)->fd;
err = inode_change_ok(dentry->d_inode, attr);
if (err)
return err;
if (append)
attr->ia_valid &= ~ATTR_SIZE;
attrs.ia_valid = 0;
if (attr->ia_valid & ATTR_MODE) {
attrs.ia_valid |= HOSTFS_ATTR_MODE;
attrs.ia_mode = attr->ia_mode;
}
if (attr->ia_valid & ATTR_UID) {
attrs.ia_valid |= HOSTFS_ATTR_UID;
attrs.ia_uid = attr->ia_uid;
}
if (attr->ia_valid & ATTR_GID) {
attrs.ia_valid |= HOSTFS_ATTR_GID;
attrs.ia_gid = attr->ia_gid;
}
if (attr->ia_valid & ATTR_SIZE) {
attrs.ia_valid |= HOSTFS_ATTR_SIZE;
attrs.ia_size = attr->ia_size;
}
if (attr->ia_valid & ATTR_ATIME) {
attrs.ia_valid |= HOSTFS_ATTR_ATIME;
attrs.ia_atime = attr->ia_atime;
}
if (attr->ia_valid & ATTR_MTIME) {
attrs.ia_valid |= HOSTFS_ATTR_MTIME;
attrs.ia_mtime = attr->ia_mtime;
}
if (attr->ia_valid & ATTR_CTIME) {
attrs.ia_valid |= HOSTFS_ATTR_CTIME;
attrs.ia_ctime = attr->ia_ctime;
}
if (attr->ia_valid & ATTR_ATIME_SET) {
attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
}
if (attr->ia_valid & ATTR_MTIME_SET) {
attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
}
name = dentry_name(dentry, 0);
if (name == NULL)
return -ENOMEM;
err = set_attr(name, &attrs, fd);
kfree(name);
if (err)
return err;
return inode_setattr(dentry->d_inode, attr);
}
static const struct inode_operations hostfs_iops = {
.create = hostfs_create,
.link = hostfs_link,
.unlink = hostfs_unlink,
.symlink = hostfs_symlink,
.mkdir = hostfs_mkdir,
.rmdir = hostfs_rmdir,
.mknod = hostfs_mknod,
.rename = hostfs_rename,
.permission = hostfs_permission,
.setattr = hostfs_setattr,
};
static const struct inode_operations hostfs_dir_iops = {
.create = hostfs_create,
.lookup = hostfs_lookup,
.link = hostfs_link,
.unlink = hostfs_unlink,
.symlink = hostfs_symlink,
.mkdir = hostfs_mkdir,
.rmdir = hostfs_rmdir,
.mknod = hostfs_mknod,
.rename = hostfs_rename,
.permission = hostfs_permission,
.setattr = hostfs_setattr,
};
int hostfs_link_readpage(struct file *file, struct page *page)
{
char *buffer, *name;
int err;
buffer = kmap(page);
name = inode_name(page->mapping->host, 0);
if (name == NULL)
return -ENOMEM;
err = hostfs_do_readlink(name, buffer, PAGE_CACHE_SIZE);
kfree(name);
if (err == PAGE_CACHE_SIZE)
err = -E2BIG;
else if (err > 0) {
flush_dcache_page(page);
SetPageUptodate(page);
if (PageError(page)) ClearPageError(page);
err = 0;
}
kunmap(page);
unlock_page(page);
return err;
}
static const struct address_space_operations hostfs_link_aops = {
.readpage = hostfs_link_readpage,
};
static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
{
struct inode *root_inode;
char *host_root_path, *req_root = d;
int err;
sb->s_blocksize = 1024;
sb->s_blocksize_bits = 10;
sb->s_magic = HOSTFS_SUPER_MAGIC;
sb->s_op = &hostfs_sbops;
sb->s_maxbytes = MAX_LFS_FILESIZE;
/* NULL is printed as <NULL> by sprintf: avoid that. */
if (req_root == NULL)
req_root = "";
err = -ENOMEM;
host_root_path = kmalloc(strlen(root_ino) + 1
+ strlen(req_root) + 1, GFP_KERNEL);
if (host_root_path == NULL)
goto out;
sprintf(host_root_path, "%s/%s", root_ino, req_root);
root_inode = hostfs_iget(sb);
if (IS_ERR(root_inode)) {
err = PTR_ERR(root_inode);
goto out_free;
}
err = init_inode(root_inode, NULL);
if (err)
goto out_put;
HOSTFS_I(root_inode)->host_filename = host_root_path;
/*
* Avoid that in the error path, iput(root_inode) frees again
* host_root_path through hostfs_destroy_inode!
*/
host_root_path = NULL;
err = -ENOMEM;
sb->s_root = d_alloc_root(root_inode);
if (sb->s_root == NULL)
goto out_put;
err = hostfs_read_inode(root_inode);
if (err) {
/* No iput in this case because the dput does that for us */
dput(sb->s_root);
sb->s_root = NULL;
goto out;
}
return 0;
out_put:
iput(root_inode);
out_free:
kfree(host_root_path);
out:
return err;
}
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 17:02:57 +08:00
static int hostfs_read_sb(struct file_system_type *type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt)
{
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 17:02:57 +08:00
return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
}
static struct file_system_type hostfs_type = {
.owner = THIS_MODULE,
.name = "hostfs",
.get_sb = hostfs_read_sb,
.kill_sb = kill_anon_super,
.fs_flags = 0,
};
static int __init init_hostfs(void)
{
return register_filesystem(&hostfs_type);
}
static void __exit exit_hostfs(void)
{
unregister_filesystem(&hostfs_type);
}
module_init(init_hostfs)
module_exit(exit_hostfs)
MODULE_LICENSE("GPL");