linux/fs/hugetlbfs/inode.c
Mike Kravetz 15568299b7 hugetlbfs: prevent filesystem stacking of hugetlbfs
syzbot found issues with having hugetlbfs on a union/overlay as reported
in [1].  Due to the limitations (no write) and special functionality of
hugetlbfs, it does not work well in filesystem stacking.  There are no
know use cases for hugetlbfs stacking.  Rather than making modifications
to get hugetlbfs working in such environments, simply prevent stacking.

[1] https://lore.kernel.org/linux-mm/000000000000b4684e05a2968ca6@google.com/

Reported-by: syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Colin Walters <walters@verbum.org>
Link: http://lkml.kernel.org/r/80f869aa-810d-ef6c-8888-b46cee135907@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 10:57:56 -07:00

1590 lines
41 KiB
C

/*
* hugetlbpage-backed filesystem. Based on ramfs.
*
* Nadia Yvette Chambers, 2002
*
* Copyright (C) 2002 Linus Torvalds.
* License: GPL
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/thread_info.h>
#include <asm/current.h>
#include <linux/sched/signal.h> /* remove ASAP */
#include <linux/falloc.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/kernel.h>
#include <linux/writeback.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/capability.h>
#include <linux/ctype.h>
#include <linux/backing-dev.h>
#include <linux/hugetlb.h>
#include <linux/pagevec.h>
#include <linux/fs_parser.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/dnotify.h>
#include <linux/statfs.h>
#include <linux/security.h>
#include <linux/magic.h>
#include <linux/migrate.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <linux/sched/mm.h>
static const struct super_operations hugetlbfs_ops;
static const struct address_space_operations hugetlbfs_aops;
const struct file_operations hugetlbfs_file_operations;
static const struct inode_operations hugetlbfs_dir_inode_operations;
static const struct inode_operations hugetlbfs_inode_operations;
enum hugetlbfs_size_type { NO_SIZE, SIZE_STD, SIZE_PERCENT };
struct hugetlbfs_fs_context {
struct hstate *hstate;
unsigned long long max_size_opt;
unsigned long long min_size_opt;
long max_hpages;
long nr_inodes;
long min_hpages;
enum hugetlbfs_size_type max_val_type;
enum hugetlbfs_size_type min_val_type;
kuid_t uid;
kgid_t gid;
umode_t mode;
};
int sysctl_hugetlb_shm_group;
enum hugetlb_param {
Opt_gid,
Opt_min_size,
Opt_mode,
Opt_nr_inodes,
Opt_pagesize,
Opt_size,
Opt_uid,
};
static const struct fs_parameter_spec hugetlb_fs_parameters[] = {
fsparam_u32 ("gid", Opt_gid),
fsparam_string("min_size", Opt_min_size),
fsparam_u32 ("mode", Opt_mode),
fsparam_string("nr_inodes", Opt_nr_inodes),
fsparam_string("pagesize", Opt_pagesize),
fsparam_string("size", Opt_size),
fsparam_u32 ("uid", Opt_uid),
{}
};
#ifdef CONFIG_NUMA
static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
struct inode *inode, pgoff_t index)
{
vma->vm_policy = mpol_shared_policy_lookup(&HUGETLBFS_I(inode)->policy,
index);
}
static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
{
mpol_cond_put(vma->vm_policy);
}
#else
static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
struct inode *inode, pgoff_t index)
{
}
static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
{
}
#endif
static void huge_pagevec_release(struct pagevec *pvec)
{
int i;
for (i = 0; i < pagevec_count(pvec); ++i)
put_page(pvec->pages[i]);
pagevec_reinit(pvec);
}
/*
* Mask used when checking the page offset value passed in via system
* calls. This value will be converted to a loff_t which is signed.
* Therefore, we want to check the upper PAGE_SHIFT + 1 bits of the
* value. The extra bit (- 1 in the shift value) is to take the sign
* bit into account.
*/
#define PGOFF_LOFFT_MAX \
(((1UL << (PAGE_SHIFT + 1)) - 1) << (BITS_PER_LONG - (PAGE_SHIFT + 1)))
static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file_inode(file);
loff_t len, vma_len;
int ret;
struct hstate *h = hstate_file(file);
/*
* vma address alignment (but not the pgoff alignment) has
* already been checked by prepare_hugepage_range. If you add
* any error returns here, do so after setting VM_HUGETLB, so
* is_vm_hugetlb_page tests below unmap_region go the right
* way when do_mmap unwinds (may be important on powerpc
* and ia64).
*/
vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
vma->vm_ops = &hugetlb_vm_ops;
/*
* page based offset in vm_pgoff could be sufficiently large to
* overflow a loff_t when converted to byte offset. This can
* only happen on architectures where sizeof(loff_t) ==
* sizeof(unsigned long). So, only check in those instances.
*/
if (sizeof(unsigned long) == sizeof(loff_t)) {
if (vma->vm_pgoff & PGOFF_LOFFT_MAX)
return -EINVAL;
}
/* must be huge page aligned */
if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
return -EINVAL;
vma_len = (loff_t)(vma->vm_end - vma->vm_start);
len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
/* check for overflow */
if (len < vma_len)
return -EINVAL;
inode_lock(inode);
file_accessed(file);
ret = -ENOMEM;
if (hugetlb_reserve_pages(inode,
vma->vm_pgoff >> huge_page_order(h),
len >> huge_page_shift(h), vma,
vma->vm_flags))
goto out;
ret = 0;
if (vma->vm_flags & VM_WRITE && inode->i_size < len)
i_size_write(inode, len);
out:
inode_unlock(inode);
return ret;
}
/*
* Called under mmap_write_lock(mm).
*/
#ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
static unsigned long
hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
struct vm_unmapped_area_info info;
info.flags = 0;
info.length = len;
info.low_limit = current->mm->mmap_base;
info.high_limit = TASK_SIZE;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
info.align_offset = 0;
return vm_unmapped_area(&info);
}
static unsigned long
hugetlb_get_unmapped_area_topdown(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
struct vm_unmapped_area_info info;
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.low_limit = max(PAGE_SIZE, mmap_min_addr);
info.high_limit = current->mm->mmap_base;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
if (unlikely(offset_in_page(addr))) {
VM_BUG_ON(addr != -ENOMEM);
info.flags = 0;
info.low_limit = current->mm->mmap_base;
info.high_limit = TASK_SIZE;
addr = vm_unmapped_area(&info);
}
return addr;
}
static unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct hstate *h = hstate_file(file);
if (len & ~huge_page_mask(h))
return -EINVAL;
if (len > TASK_SIZE)
return -ENOMEM;
if (flags & MAP_FIXED) {
if (prepare_hugepage_range(file, addr, len))
return -EINVAL;
return addr;
}
if (addr) {
addr = ALIGN(addr, huge_page_size(h));
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
(!vma || addr + len <= vm_start_gap(vma)))
return addr;
}
/*
* Use mm->get_unmapped_area value as a hint to use topdown routine.
* If architectures have special needs, they should define their own
* version of hugetlb_get_unmapped_area.
*/
if (mm->get_unmapped_area == arch_get_unmapped_area_topdown)
return hugetlb_get_unmapped_area_topdown(file, addr, len,
pgoff, flags);
return hugetlb_get_unmapped_area_bottomup(file, addr, len,
pgoff, flags);
}
#endif
static size_t
hugetlbfs_read_actor(struct page *page, unsigned long offset,
struct iov_iter *to, unsigned long size)
{
size_t copied = 0;
int i, chunksize;
/* Find which 4k chunk and offset with in that chunk */
i = offset >> PAGE_SHIFT;
offset = offset & ~PAGE_MASK;
while (size) {
size_t n;
chunksize = PAGE_SIZE;
if (offset)
chunksize -= offset;
if (chunksize > size)
chunksize = size;
n = copy_page_to_iter(&page[i], offset, chunksize, to);
copied += n;
if (n != chunksize)
return copied;
offset = 0;
size -= chunksize;
i++;
}
return copied;
}
/*
* Support for read() - Find the page attached to f_mapping and copy out the
* data. Its *very* similar to do_generic_mapping_read(), we can't use that
* since it has PAGE_SIZE assumptions.
*/
static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct hstate *h = hstate_file(file);
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
unsigned long index = iocb->ki_pos >> huge_page_shift(h);
unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
unsigned long end_index;
loff_t isize;
ssize_t retval = 0;
while (iov_iter_count(to)) {
struct page *page;
size_t nr, copied;
/* nr is the maximum number of bytes to copy from this page */
nr = huge_page_size(h);
isize = i_size_read(inode);
if (!isize)
break;
end_index = (isize - 1) >> huge_page_shift(h);
if (index > end_index)
break;
if (index == end_index) {
nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
if (nr <= offset)
break;
}
nr = nr - offset;
/* Find the page */
page = find_lock_page(mapping, index);
if (unlikely(page == NULL)) {
/*
* We have a HOLE, zero out the user-buffer for the
* length of the hole or request.
*/
copied = iov_iter_zero(nr, to);
} else {
unlock_page(page);
/*
* We have the page, copy it to user space buffer.
*/
copied = hugetlbfs_read_actor(page, offset, to, nr);
put_page(page);
}
offset += copied;
retval += copied;
if (copied != nr && iov_iter_count(to)) {
if (!retval)
retval = -EFAULT;
break;
}
index += offset >> huge_page_shift(h);
offset &= ~huge_page_mask(h);
}
iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
return retval;
}
static int hugetlbfs_write_begin(struct file *file,
struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
return -EINVAL;
}
static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
BUG();
return -EINVAL;
}
static void remove_huge_page(struct page *page)
{
ClearPageDirty(page);
ClearPageUptodate(page);
delete_from_page_cache(page);
}
static void
hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end)
{
struct vm_area_struct *vma;
/*
* end == 0 indicates that the entire range after
* start should be unmapped.
*/
vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
unsigned long v_offset;
unsigned long v_end;
/*
* Can the expression below overflow on 32-bit arches?
* No, because the interval tree returns us only those vmas
* which overlap the truncated area starting at pgoff,
* and no vma on a 32-bit arch can span beyond the 4GB.
*/
if (vma->vm_pgoff < start)
v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
else
v_offset = 0;
if (!end)
v_end = vma->vm_end;
else {
v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
+ vma->vm_start;
if (v_end > vma->vm_end)
v_end = vma->vm_end;
}
unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
NULL);
}
}
/*
* remove_inode_hugepages handles two distinct cases: truncation and hole
* punch. There are subtle differences in operation for each case.
*
* truncation is indicated by end of range being LLONG_MAX
* In this case, we first scan the range and release found pages.
* After releasing pages, hugetlb_unreserve_pages cleans up region/reserv
* maps and global counts. Page faults can not race with truncation
* in this routine. hugetlb_no_page() holds i_mmap_rwsem and prevents
* page faults in the truncated range by checking i_size. i_size is
* modified while holding i_mmap_rwsem.
* hole punch is indicated if end is not LLONG_MAX
* In the hole punch case we scan the range and release found pages.
* Only when releasing a page is the associated region/reserv map
* deleted. The region/reserv map for ranges without associated
* pages are not modified. Page faults can race with hole punch.
* This is indicated if we find a mapped page.
* Note: If the passed end of range value is beyond the end of file, but
* not LLONG_MAX this routine still performs a hole punch operation.
*/
static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
loff_t lend)
{
struct hstate *h = hstate_inode(inode);
struct address_space *mapping = &inode->i_data;
const pgoff_t start = lstart >> huge_page_shift(h);
const pgoff_t end = lend >> huge_page_shift(h);
struct vm_area_struct pseudo_vma;
struct pagevec pvec;
pgoff_t next, index;
int i, freed = 0;
bool truncate_op = (lend == LLONG_MAX);
vma_init(&pseudo_vma, current->mm);
pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
pagevec_init(&pvec);
next = start;
while (next < end) {
/*
* When no more pages are found, we are done.
*/
if (!pagevec_lookup_range(&pvec, mapping, &next, end - 1))
break;
for (i = 0; i < pagevec_count(&pvec); ++i) {
struct page *page = pvec.pages[i];
u32 hash;
index = page->index;
hash = hugetlb_fault_mutex_hash(mapping, index);
if (!truncate_op) {
/*
* Only need to hold the fault mutex in the
* hole punch case. This prevents races with
* page faults. Races are not possible in the
* case of truncation.
*/
mutex_lock(&hugetlb_fault_mutex_table[hash]);
}
/*
* If page is mapped, it was faulted in after being
* unmapped in caller. Unmap (again) now after taking
* the fault mutex. The mutex will prevent faults
* until we finish removing the page.
*
* This race can only happen in the hole punch case.
* Getting here in a truncate operation is a bug.
*/
if (unlikely(page_mapped(page))) {
BUG_ON(truncate_op);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
i_mmap_lock_write(mapping);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
hugetlb_vmdelete_list(&mapping->i_mmap,
index * pages_per_huge_page(h),
(index + 1) * pages_per_huge_page(h));
i_mmap_unlock_write(mapping);
}
lock_page(page);
/*
* We must free the huge page and remove from page
* cache (remove_huge_page) BEFORE removing the
* region/reserve map (hugetlb_unreserve_pages). In
* rare out of memory conditions, removal of the
* region/reserve map could fail. Correspondingly,
* the subpool and global reserve usage count can need
* to be adjusted.
*/
VM_BUG_ON(PagePrivate(page));
remove_huge_page(page);
freed++;
if (!truncate_op) {
if (unlikely(hugetlb_unreserve_pages(inode,
index, index + 1, 1)))
hugetlb_fix_reserve_counts(inode);
}
unlock_page(page);
if (!truncate_op)
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
}
huge_pagevec_release(&pvec);
cond_resched();
}
if (truncate_op)
(void)hugetlb_unreserve_pages(inode, start, LONG_MAX, freed);
}
static void hugetlbfs_evict_inode(struct inode *inode)
{
struct resv_map *resv_map;
remove_inode_hugepages(inode, 0, LLONG_MAX);
/*
* Get the resv_map from the address space embedded in the inode.
* This is the address space which points to any resv_map allocated
* at inode creation time. If this is a device special inode,
* i_mapping may not point to the original address space.
*/
resv_map = (struct resv_map *)(&inode->i_data)->private_data;
/* Only regular and link inodes have associated reserve maps */
if (resv_map)
resv_map_release(&resv_map->refs);
clear_inode(inode);
}
static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
{
pgoff_t pgoff;
struct address_space *mapping = inode->i_mapping;
struct hstate *h = hstate_inode(inode);
BUG_ON(offset & ~huge_page_mask(h));
pgoff = offset >> PAGE_SHIFT;
i_mmap_lock_write(mapping);
i_size_write(inode, offset);
if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0);
i_mmap_unlock_write(mapping);
remove_inode_hugepages(inode, offset, LLONG_MAX);
return 0;
}
static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
{
struct hstate *h = hstate_inode(inode);
loff_t hpage_size = huge_page_size(h);
loff_t hole_start, hole_end;
/*
* For hole punch round up the beginning offset of the hole and
* round down the end.
*/
hole_start = round_up(offset, hpage_size);
hole_end = round_down(offset + len, hpage_size);
if (hole_end > hole_start) {
struct address_space *mapping = inode->i_mapping;
struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
inode_lock(inode);
/* protected by i_mutex */
if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
inode_unlock(inode);
return -EPERM;
}
i_mmap_lock_write(mapping);
if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
hugetlb_vmdelete_list(&mapping->i_mmap,
hole_start >> PAGE_SHIFT,
hole_end >> PAGE_SHIFT);
i_mmap_unlock_write(mapping);
remove_inode_hugepages(inode, hole_start, hole_end);
inode_unlock(inode);
}
return 0;
}
static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
struct inode *inode = file_inode(file);
struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
struct address_space *mapping = inode->i_mapping;
struct hstate *h = hstate_inode(inode);
struct vm_area_struct pseudo_vma;
struct mm_struct *mm = current->mm;
loff_t hpage_size = huge_page_size(h);
unsigned long hpage_shift = huge_page_shift(h);
pgoff_t start, index, end;
int error;
u32 hash;
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
return -EOPNOTSUPP;
if (mode & FALLOC_FL_PUNCH_HOLE)
return hugetlbfs_punch_hole(inode, offset, len);
/*
* Default preallocate case.
* For this range, start is rounded down and end is rounded up
* as well as being converted to page offsets.
*/
start = offset >> hpage_shift;
end = (offset + len + hpage_size - 1) >> hpage_shift;
inode_lock(inode);
/* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
error = inode_newsize_ok(inode, offset + len);
if (error)
goto out;
if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
error = -EPERM;
goto out;
}
/*
* Initialize a pseudo vma as this is required by the huge page
* allocation routines. If NUMA is configured, use page index
* as input to create an allocation policy.
*/
vma_init(&pseudo_vma, mm);
pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
pseudo_vma.vm_file = file;
for (index = start; index < end; index++) {
/*
* This is supposed to be the vaddr where the page is being
* faulted in, but we have no vaddr here.
*/
struct page *page;
unsigned long addr;
int avoid_reserve = 0;
cond_resched();
/*
* fallocate(2) manpage permits EINTR; we may have been
* interrupted because we are using up too much memory.
*/
if (signal_pending(current)) {
error = -EINTR;
break;
}
/* Set numa allocation policy based on index */
hugetlb_set_vma_policy(&pseudo_vma, inode, index);
/* addr is the offset within the file (zero based) */
addr = index * hpage_size;
/*
* fault mutex taken here, protects against fault path
* and hole punch. inode_lock previously taken protects
* against truncation.
*/
hash = hugetlb_fault_mutex_hash(mapping, index);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
/* See if already present in mapping to avoid alloc/free */
page = find_get_page(mapping, index);
if (page) {
put_page(page);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
hugetlb_drop_vma_policy(&pseudo_vma);
continue;
}
/* Allocate page and add to page cache */
page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
hugetlb_drop_vma_policy(&pseudo_vma);
if (IS_ERR(page)) {
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
error = PTR_ERR(page);
goto out;
}
clear_huge_page(page, addr, pages_per_huge_page(h));
__SetPageUptodate(page);
error = huge_add_to_page_cache(page, mapping, index);
if (unlikely(error)) {
put_page(page);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
goto out;
}
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
/*
* unlock_page because locked by add_to_page_cache()
* page_put due to reference from alloc_huge_page()
*/
unlock_page(page);
put_page(page);
}
if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
i_size_write(inode, offset + len);
inode->i_ctime = current_time(inode);
out:
inode_unlock(inode);
return error;
}
static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
struct hstate *h = hstate_inode(inode);
int error;
unsigned int ia_valid = attr->ia_valid;
struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
BUG_ON(!inode);
error = setattr_prepare(dentry, attr);
if (error)
return error;
if (ia_valid & ATTR_SIZE) {
loff_t oldsize = inode->i_size;
loff_t newsize = attr->ia_size;
if (newsize & ~huge_page_mask(h))
return -EINVAL;
/* protected by i_mutex */
if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
(newsize > oldsize && (info->seals & F_SEAL_GROW)))
return -EPERM;
error = hugetlb_vmtruncate(inode, newsize);
if (error)
return error;
}
setattr_copy(inode, attr);
mark_inode_dirty(inode);
return 0;
}
static struct inode *hugetlbfs_get_root(struct super_block *sb,
struct hugetlbfs_fs_context *ctx)
{
struct inode *inode;
inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_mode = S_IFDIR | ctx->mode;
inode->i_uid = ctx->uid;
inode->i_gid = ctx->gid;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
inode->i_op = &hugetlbfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
lockdep_annotate_inode_mutex_key(inode);
}
return inode;
}
/*
* Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
* be taken from reclaim -- unlike regular filesystems. This needs an
* annotation because huge_pmd_share() does an allocation under hugetlb's
* i_mmap_rwsem.
*/
static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
static struct inode *hugetlbfs_get_inode(struct super_block *sb,
struct inode *dir,
umode_t mode, dev_t dev)
{
struct inode *inode;
struct resv_map *resv_map = NULL;
/*
* Reserve maps are only needed for inodes that can have associated
* page allocations.
*/
if (S_ISREG(mode) || S_ISLNK(mode)) {
resv_map = resv_map_alloc();
if (!resv_map)
return NULL;
}
inode = new_inode(sb);
if (inode) {
struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
inode->i_ino = get_next_ino();
inode_init_owner(inode, dir, mode);
lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
&hugetlbfs_i_mmap_rwsem_key);
inode->i_mapping->a_ops = &hugetlbfs_aops;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
inode->i_mapping->private_data = resv_map;
info->seals = F_SEAL_SEAL;
switch (mode & S_IFMT) {
default:
init_special_inode(inode, mode, dev);
break;
case S_IFREG:
inode->i_op = &hugetlbfs_inode_operations;
inode->i_fop = &hugetlbfs_file_operations;
break;
case S_IFDIR:
inode->i_op = &hugetlbfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
break;
case S_IFLNK:
inode->i_op = &page_symlink_inode_operations;
inode_nohighmem(inode);
break;
}
lockdep_annotate_inode_mutex_key(inode);
} else {
if (resv_map)
kref_put(&resv_map->refs, resv_map_release);
}
return inode;
}
/*
* File creation. Allocate an inode, and we're done..
*/
static int do_hugetlbfs_mknod(struct inode *dir,
struct dentry *dentry,
umode_t mode,
dev_t dev,
bool tmpfile)
{
struct inode *inode;
int error = -ENOSPC;
inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
if (inode) {
dir->i_ctime = dir->i_mtime = current_time(dir);
if (tmpfile) {
d_tmpfile(dentry, inode);
} else {
d_instantiate(dentry, inode);
dget(dentry);/* Extra count - pin the dentry in core */
}
error = 0;
}
return error;
}
static int hugetlbfs_mknod(struct inode *dir,
struct dentry *dentry, umode_t mode, dev_t dev)
{
return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
}
static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
if (!retval)
inc_nlink(dir);
return retval;
}
static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
{
return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
}
static int hugetlbfs_tmpfile(struct inode *dir,
struct dentry *dentry, umode_t mode)
{
return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
}
static int hugetlbfs_symlink(struct inode *dir,
struct dentry *dentry, const char *symname)
{
struct inode *inode;
int error = -ENOSPC;
inode = hugetlbfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
if (inode) {
int l = strlen(symname)+1;
error = page_symlink(inode, symname, l);
if (!error) {
d_instantiate(dentry, inode);
dget(dentry);
} else
iput(inode);
}
dir->i_ctime = dir->i_mtime = current_time(dir);
return error;
}
/*
* mark the head page dirty
*/
static int hugetlbfs_set_page_dirty(struct page *page)
{
struct page *head = compound_head(page);
SetPageDirty(head);
return 0;
}
static int hugetlbfs_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page,
enum migrate_mode mode)
{
int rc;
rc = migrate_huge_page_move_mapping(mapping, newpage, page);
if (rc != MIGRATEPAGE_SUCCESS)
return rc;
/*
* page_private is subpool pointer in hugetlb pages. Transfer to
* new page. PagePrivate is not associated with page_private for
* hugetlb pages and can not be set here as only page_huge_active
* pages can be migrated.
*/
if (page_private(page)) {
set_page_private(newpage, page_private(page));
set_page_private(page, 0);
}
if (mode != MIGRATE_SYNC_NO_COPY)
migrate_page_copy(newpage, page);
else
migrate_page_states(newpage, page);
return MIGRATEPAGE_SUCCESS;
}
static int hugetlbfs_error_remove_page(struct address_space *mapping,
struct page *page)
{
struct inode *inode = mapping->host;
pgoff_t index = page->index;
remove_huge_page(page);
if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1)))
hugetlb_fix_reserve_counts(inode);
return 0;
}
/*
* Display the mount options in /proc/mounts.
*/
static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
{
struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(root->d_sb);
struct hugepage_subpool *spool = sbinfo->spool;
unsigned long hpage_size = huge_page_size(sbinfo->hstate);
unsigned hpage_shift = huge_page_shift(sbinfo->hstate);
char mod;
if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
seq_printf(m, ",uid=%u",
from_kuid_munged(&init_user_ns, sbinfo->uid));
if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
seq_printf(m, ",gid=%u",
from_kgid_munged(&init_user_ns, sbinfo->gid));
if (sbinfo->mode != 0755)
seq_printf(m, ",mode=%o", sbinfo->mode);
if (sbinfo->max_inodes != -1)
seq_printf(m, ",nr_inodes=%lu", sbinfo->max_inodes);
hpage_size /= 1024;
mod = 'K';
if (hpage_size >= 1024) {
hpage_size /= 1024;
mod = 'M';
}
seq_printf(m, ",pagesize=%lu%c", hpage_size, mod);
if (spool) {
if (spool->max_hpages != -1)
seq_printf(m, ",size=%llu",
(unsigned long long)spool->max_hpages << hpage_shift);
if (spool->min_hpages != -1)
seq_printf(m, ",min_size=%llu",
(unsigned long long)spool->min_hpages << hpage_shift);
}
return 0;
}
static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
struct hstate *h = hstate_inode(d_inode(dentry));
buf->f_type = HUGETLBFS_MAGIC;
buf->f_bsize = huge_page_size(h);
if (sbinfo) {
spin_lock(&sbinfo->stat_lock);
/* If no limits set, just report 0 for max/free/used
* blocks, like simple_statfs() */
if (sbinfo->spool) {
long free_pages;
spin_lock(&sbinfo->spool->lock);
buf->f_blocks = sbinfo->spool->max_hpages;
free_pages = sbinfo->spool->max_hpages
- sbinfo->spool->used_hpages;
buf->f_bavail = buf->f_bfree = free_pages;
spin_unlock(&sbinfo->spool->lock);
buf->f_files = sbinfo->max_inodes;
buf->f_ffree = sbinfo->free_inodes;
}
spin_unlock(&sbinfo->stat_lock);
}
buf->f_namelen = NAME_MAX;
return 0;
}
static void hugetlbfs_put_super(struct super_block *sb)
{
struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
if (sbi) {
sb->s_fs_info = NULL;
if (sbi->spool)
hugepage_put_subpool(sbi->spool);
kfree(sbi);
}
}
static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
{
if (sbinfo->free_inodes >= 0) {
spin_lock(&sbinfo->stat_lock);
if (unlikely(!sbinfo->free_inodes)) {
spin_unlock(&sbinfo->stat_lock);
return 0;
}
sbinfo->free_inodes--;
spin_unlock(&sbinfo->stat_lock);
}
return 1;
}
static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
{
if (sbinfo->free_inodes >= 0) {
spin_lock(&sbinfo->stat_lock);
sbinfo->free_inodes++;
spin_unlock(&sbinfo->stat_lock);
}
}
static struct kmem_cache *hugetlbfs_inode_cachep;
static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
{
struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
struct hugetlbfs_inode_info *p;
if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
return NULL;
p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
if (unlikely(!p)) {
hugetlbfs_inc_free_inodes(sbinfo);
return NULL;
}
/*
* Any time after allocation, hugetlbfs_destroy_inode can be called
* for the inode. mpol_free_shared_policy is unconditionally called
* as part of hugetlbfs_destroy_inode. So, initialize policy here
* in case of a quick call to destroy.
*
* Note that the policy is initialized even if we are creating a
* private inode. This simplifies hugetlbfs_destroy_inode.
*/
mpol_shared_policy_init(&p->policy, NULL);
return &p->vfs_inode;
}
static void hugetlbfs_free_inode(struct inode *inode)
{
kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
}
static void hugetlbfs_destroy_inode(struct inode *inode)
{
hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
}
static const struct address_space_operations hugetlbfs_aops = {
.write_begin = hugetlbfs_write_begin,
.write_end = hugetlbfs_write_end,
.set_page_dirty = hugetlbfs_set_page_dirty,
.migratepage = hugetlbfs_migrate_page,
.error_remove_page = hugetlbfs_error_remove_page,
};
static void init_once(void *foo)
{
struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
inode_init_once(&ei->vfs_inode);
}
const struct file_operations hugetlbfs_file_operations = {
.read_iter = hugetlbfs_read_iter,
.mmap = hugetlbfs_file_mmap,
.fsync = noop_fsync,
.get_unmapped_area = hugetlb_get_unmapped_area,
.llseek = default_llseek,
.fallocate = hugetlbfs_fallocate,
};
static const struct inode_operations hugetlbfs_dir_inode_operations = {
.create = hugetlbfs_create,
.lookup = simple_lookup,
.link = simple_link,
.unlink = simple_unlink,
.symlink = hugetlbfs_symlink,
.mkdir = hugetlbfs_mkdir,
.rmdir = simple_rmdir,
.mknod = hugetlbfs_mknod,
.rename = simple_rename,
.setattr = hugetlbfs_setattr,
.tmpfile = hugetlbfs_tmpfile,
};
static const struct inode_operations hugetlbfs_inode_operations = {
.setattr = hugetlbfs_setattr,
};
static const struct super_operations hugetlbfs_ops = {
.alloc_inode = hugetlbfs_alloc_inode,
.free_inode = hugetlbfs_free_inode,
.destroy_inode = hugetlbfs_destroy_inode,
.evict_inode = hugetlbfs_evict_inode,
.statfs = hugetlbfs_statfs,
.put_super = hugetlbfs_put_super,
.show_options = hugetlbfs_show_options,
};
/*
* Convert size option passed from command line to number of huge pages
* in the pool specified by hstate. Size option could be in bytes
* (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
*/
static long
hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
enum hugetlbfs_size_type val_type)
{
if (val_type == NO_SIZE)
return -1;
if (val_type == SIZE_PERCENT) {
size_opt <<= huge_page_shift(h);
size_opt *= h->max_huge_pages;
do_div(size_opt, 100);
}
size_opt >>= huge_page_shift(h);
return size_opt;
}
/*
* Parse one mount parameter.
*/
static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct hugetlbfs_fs_context *ctx = fc->fs_private;
struct fs_parse_result result;
char *rest;
unsigned long ps;
int opt;
opt = fs_parse(fc, hugetlb_fs_parameters, param, &result);
if (opt < 0)
return opt;
switch (opt) {
case Opt_uid:
ctx->uid = make_kuid(current_user_ns(), result.uint_32);
if (!uid_valid(ctx->uid))
goto bad_val;
return 0;
case Opt_gid:
ctx->gid = make_kgid(current_user_ns(), result.uint_32);
if (!gid_valid(ctx->gid))
goto bad_val;
return 0;
case Opt_mode:
ctx->mode = result.uint_32 & 01777U;
return 0;
case Opt_size:
/* memparse() will accept a K/M/G without a digit */
if (!isdigit(param->string[0]))
goto bad_val;
ctx->max_size_opt = memparse(param->string, &rest);
ctx->max_val_type = SIZE_STD;
if (*rest == '%')
ctx->max_val_type = SIZE_PERCENT;
return 0;
case Opt_nr_inodes:
/* memparse() will accept a K/M/G without a digit */
if (!isdigit(param->string[0]))
goto bad_val;
ctx->nr_inodes = memparse(param->string, &rest);
return 0;
case Opt_pagesize:
ps = memparse(param->string, &rest);
ctx->hstate = size_to_hstate(ps);
if (!ctx->hstate) {
pr_err("Unsupported page size %lu MB\n", ps >> 20);
return -EINVAL;
}
return 0;
case Opt_min_size:
/* memparse() will accept a K/M/G without a digit */
if (!isdigit(param->string[0]))
goto bad_val;
ctx->min_size_opt = memparse(param->string, &rest);
ctx->min_val_type = SIZE_STD;
if (*rest == '%')
ctx->min_val_type = SIZE_PERCENT;
return 0;
default:
return -EINVAL;
}
bad_val:
return invalfc(fc, "Bad value '%s' for mount option '%s'\n",
param->string, param->key);
}
/*
* Validate the parsed options.
*/
static int hugetlbfs_validate(struct fs_context *fc)
{
struct hugetlbfs_fs_context *ctx = fc->fs_private;
/*
* Use huge page pool size (in hstate) to convert the size
* options to number of huge pages. If NO_SIZE, -1 is returned.
*/
ctx->max_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
ctx->max_size_opt,
ctx->max_val_type);
ctx->min_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
ctx->min_size_opt,
ctx->min_val_type);
/*
* If max_size was specified, then min_size must be smaller
*/
if (ctx->max_val_type > NO_SIZE &&
ctx->min_hpages > ctx->max_hpages) {
pr_err("Minimum size can not be greater than maximum size\n");
return -EINVAL;
}
return 0;
}
static int
hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct hugetlbfs_fs_context *ctx = fc->fs_private;
struct hugetlbfs_sb_info *sbinfo;
sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
if (!sbinfo)
return -ENOMEM;
sb->s_fs_info = sbinfo;
spin_lock_init(&sbinfo->stat_lock);
sbinfo->hstate = ctx->hstate;
sbinfo->max_inodes = ctx->nr_inodes;
sbinfo->free_inodes = ctx->nr_inodes;
sbinfo->spool = NULL;
sbinfo->uid = ctx->uid;
sbinfo->gid = ctx->gid;
sbinfo->mode = ctx->mode;
/*
* Allocate and initialize subpool if maximum or minimum size is
* specified. Any needed reservations (for minimim size) are taken
* taken when the subpool is created.
*/
if (ctx->max_hpages != -1 || ctx->min_hpages != -1) {
sbinfo->spool = hugepage_new_subpool(ctx->hstate,
ctx->max_hpages,
ctx->min_hpages);
if (!sbinfo->spool)
goto out_free;
}
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_blocksize = huge_page_size(ctx->hstate);
sb->s_blocksize_bits = huge_page_shift(ctx->hstate);
sb->s_magic = HUGETLBFS_MAGIC;
sb->s_op = &hugetlbfs_ops;
sb->s_time_gran = 1;
/*
* Due to the special and limited functionality of hugetlbfs, it does
* not work well as a stacking filesystem.
*/
sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx));
if (!sb->s_root)
goto out_free;
return 0;
out_free:
kfree(sbinfo->spool);
kfree(sbinfo);
return -ENOMEM;
}
static int hugetlbfs_get_tree(struct fs_context *fc)
{
int err = hugetlbfs_validate(fc);
if (err)
return err;
return get_tree_nodev(fc, hugetlbfs_fill_super);
}
static void hugetlbfs_fs_context_free(struct fs_context *fc)
{
kfree(fc->fs_private);
}
static const struct fs_context_operations hugetlbfs_fs_context_ops = {
.free = hugetlbfs_fs_context_free,
.parse_param = hugetlbfs_parse_param,
.get_tree = hugetlbfs_get_tree,
};
static int hugetlbfs_init_fs_context(struct fs_context *fc)
{
struct hugetlbfs_fs_context *ctx;
ctx = kzalloc(sizeof(struct hugetlbfs_fs_context), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->max_hpages = -1; /* No limit on size by default */
ctx->nr_inodes = -1; /* No limit on number of inodes by default */
ctx->uid = current_fsuid();
ctx->gid = current_fsgid();
ctx->mode = 0755;
ctx->hstate = &default_hstate;
ctx->min_hpages = -1; /* No default minimum size */
ctx->max_val_type = NO_SIZE;
ctx->min_val_type = NO_SIZE;
fc->fs_private = ctx;
fc->ops = &hugetlbfs_fs_context_ops;
return 0;
}
static struct file_system_type hugetlbfs_fs_type = {
.name = "hugetlbfs",
.init_fs_context = hugetlbfs_init_fs_context,
.parameters = hugetlb_fs_parameters,
.kill_sb = kill_litter_super,
};
static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
static int can_do_hugetlb_shm(void)
{
kgid_t shm_group;
shm_group = make_kgid(&init_user_ns, sysctl_hugetlb_shm_group);
return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
}
static int get_hstate_idx(int page_size_log)
{
struct hstate *h = hstate_sizelog(page_size_log);
if (!h)
return -1;
return h - hstates;
}
/*
* Note that size should be aligned to proper hugepage size in caller side,
* otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
*/
struct file *hugetlb_file_setup(const char *name, size_t size,
vm_flags_t acctflag, struct user_struct **user,
int creat_flags, int page_size_log)
{
struct inode *inode;
struct vfsmount *mnt;
int hstate_idx;
struct file *file;
hstate_idx = get_hstate_idx(page_size_log);
if (hstate_idx < 0)
return ERR_PTR(-ENODEV);
*user = NULL;
mnt = hugetlbfs_vfsmount[hstate_idx];
if (!mnt)
return ERR_PTR(-ENOENT);
if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
*user = current_user();
if (user_shm_lock(size, *user)) {
task_lock(current);
pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
current->comm, current->pid);
task_unlock(current);
} else {
*user = NULL;
return ERR_PTR(-EPERM);
}
}
file = ERR_PTR(-ENOSPC);
inode = hugetlbfs_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0);
if (!inode)
goto out;
if (creat_flags == HUGETLB_SHMFS_INODE)
inode->i_flags |= S_PRIVATE;
inode->i_size = size;
clear_nlink(inode);
if (hugetlb_reserve_pages(inode, 0,
size >> huge_page_shift(hstate_inode(inode)), NULL,
acctflag))
file = ERR_PTR(-ENOMEM);
else
file = alloc_file_pseudo(inode, mnt, name, O_RDWR,
&hugetlbfs_file_operations);
if (!IS_ERR(file))
return file;
iput(inode);
out:
if (*user) {
user_shm_unlock(size, *user);
*user = NULL;
}
return file;
}
static struct vfsmount *__init mount_one_hugetlbfs(struct hstate *h)
{
struct fs_context *fc;
struct vfsmount *mnt;
fc = fs_context_for_mount(&hugetlbfs_fs_type, SB_KERNMOUNT);
if (IS_ERR(fc)) {
mnt = ERR_CAST(fc);
} else {
struct hugetlbfs_fs_context *ctx = fc->fs_private;
ctx->hstate = h;
mnt = fc_mount(fc);
put_fs_context(fc);
}
if (IS_ERR(mnt))
pr_err("Cannot mount internal hugetlbfs for page size %uK",
1U << (h->order + PAGE_SHIFT - 10));
return mnt;
}
static int __init init_hugetlbfs_fs(void)
{
struct vfsmount *mnt;
struct hstate *h;
int error;
int i;
if (!hugepages_supported()) {
pr_info("disabling because there are no supported hugepage sizes\n");
return -ENOTSUPP;
}
error = -ENOMEM;
hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
sizeof(struct hugetlbfs_inode_info),
0, SLAB_ACCOUNT, init_once);
if (hugetlbfs_inode_cachep == NULL)
goto out;
error = register_filesystem(&hugetlbfs_fs_type);
if (error)
goto out_free;
/* default hstate mount is required */
mnt = mount_one_hugetlbfs(&hstates[default_hstate_idx]);
if (IS_ERR(mnt)) {
error = PTR_ERR(mnt);
goto out_unreg;
}
hugetlbfs_vfsmount[default_hstate_idx] = mnt;
/* other hstates are optional */
i = 0;
for_each_hstate(h) {
if (i == default_hstate_idx) {
i++;
continue;
}
mnt = mount_one_hugetlbfs(h);
if (IS_ERR(mnt))
hugetlbfs_vfsmount[i] = NULL;
else
hugetlbfs_vfsmount[i] = mnt;
i++;
}
return 0;
out_unreg:
(void)unregister_filesystem(&hugetlbfs_fs_type);
out_free:
kmem_cache_destroy(hugetlbfs_inode_cachep);
out:
return error;
}
fs_initcall(init_hugetlbfs_fs)