Logo Search packages:      
Sourcecode: linux version File versions  Download package

inode.c

/*
 * hugetlbpage-backed filesystem.  Based on ramfs.
 *
 * William Irwin, 2002
 *
 * Copyright (C) 2002 Linus Torvalds.
 */

#include <linux/module.h>
#include <linux/thread_info.h>
#include <asm/current.h>
#include <linux/sched.h>            /* remove ASAP */
#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/parser.h>
#include <linux/mman.h>
#include <linux/quotaops.h>
#include <linux/slab.h>
#include <linux/dnotify.h>
#include <linux/statfs.h>
#include <linux/security.h>

#include <asm/uaccess.h>

/* some random number */
#define HUGETLBFS_MAGIC 0x958458f6

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;

static struct backing_dev_info hugetlbfs_backing_dev_info = {
      .ra_pages   = 0,  /* No readahead */
      .capabilities     = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
};

int sysctl_hugetlb_shm_group;

enum {
      Opt_size, Opt_nr_inodes,
      Opt_mode, Opt_uid, Opt_gid,
      Opt_err,
};

static match_table_t tokens = {
      {Opt_size,  "size=%s"},
      {Opt_nr_inodes,   "nr_inodes=%s"},
      {Opt_mode,  "mode=%o"},
      {Opt_uid,   "uid=%u"},
      {Opt_gid,   "gid=%u"},
      {Opt_err,   NULL},
};

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);
}

static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
      struct inode *inode = file->f_path.dentry->d_inode;
      loff_t len, vma_len;
      int ret;

      /*
       * 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_pgoff unwinds (may be important on powerpc
       * and ia64).
       */
      vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
      vma->vm_ops = &hugetlb_vm_ops;

      if (vma->vm_pgoff & ~(HPAGE_MASK >> PAGE_SHIFT))
            return -EINVAL;

      vma_len = (loff_t)(vma->vm_end - vma->vm_start);

      mutex_lock(&inode->i_mutex);
      file_accessed(file);

      ret = -ENOMEM;
      len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);

      if (vma->vm_flags & VM_MAYSHARE &&
          hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
                          len >> HPAGE_SHIFT))
            goto out;

      ret = 0;
      hugetlb_prefault_arch_hook(vma->vm_mm);
      if (vma->vm_flags & VM_WRITE && inode->i_size < len)
            inode->i_size = len;
out:
      mutex_unlock(&inode->i_mutex);

      return ret;
}

/*
 * Called under down_write(mmap_sem).
 */

#ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
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;
      unsigned long start_addr;

      if (len & ~HPAGE_MASK)
            return -EINVAL;
      if (len > TASK_SIZE)
            return -ENOMEM;

      if (flags & MAP_FIXED) {
            if (prepare_hugepage_range(addr, len))
                  return -EINVAL;
            return addr;
      }

      if (addr) {
            addr = ALIGN(addr, HPAGE_SIZE);
            vma = find_vma(mm, addr);
            if (TASK_SIZE - len >= addr &&
                (!vma || addr + len <= vma->vm_start))
                  return addr;
      }

      start_addr = mm->free_area_cache;

      if (len <= mm->cached_hole_size)
            start_addr = TASK_UNMAPPED_BASE;

full_search:
      addr = ALIGN(start_addr, HPAGE_SIZE);

      for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
            /* At this point:  (!vma || addr < vma->vm_end). */
            if (TASK_SIZE - len < addr) {
                  /*
                   * Start a new search - just in case we missed
                   * some holes.
                   */
                  if (start_addr != TASK_UNMAPPED_BASE) {
                        start_addr = TASK_UNMAPPED_BASE;
                        goto full_search;
                  }
                  return -ENOMEM;
            }

            if (!vma || addr + len <= vma->vm_start)
                  return addr;
            addr = ALIGN(vma->vm_end, HPAGE_SIZE);
      }
}
#endif

static int
hugetlbfs_read_actor(struct page *page, unsigned long offset,
                  char __user *buf, unsigned long count,
                  unsigned long size)
{
      char *kaddr;
      unsigned long left, copied = 0;
      int i, chunksize;

      if (size > count)
            size = count;

      /* Find which 4k chunk and offset with in that chunk */
      i = offset >> PAGE_CACHE_SHIFT;
      offset = offset & ~PAGE_CACHE_MASK;

      while (size) {
            chunksize = PAGE_CACHE_SIZE;
            if (offset)
                  chunksize -= offset;
            if (chunksize > size)
                  chunksize = size;
            kaddr = kmap(&page[i]);
            left = __copy_to_user(buf, kaddr + offset, chunksize);
            kunmap(&page[i]);
            if (left) {
                  copied += (chunksize - left);
                  break;
            }
            offset = 0;
            size -= chunksize;
            buf += chunksize;
            copied += chunksize;
            i++;
      }
      return copied ? copied : -EFAULT;
}

/*
 * 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_CACHE_SIZE assumptions.
 */
static ssize_t hugetlbfs_read(struct file *filp, char __user *buf,
                        size_t len, loff_t *ppos)
{
      struct address_space *mapping = filp->f_mapping;
      struct inode *inode = mapping->host;
      unsigned long index = *ppos >> HPAGE_SHIFT;
      unsigned long offset = *ppos & ~HPAGE_MASK;
      unsigned long end_index;
      loff_t isize;
      ssize_t retval = 0;

      mutex_lock(&inode->i_mutex);

      /* validate length */
      if (len == 0)
            goto out;

      isize = i_size_read(inode);
      if (!isize)
            goto out;

      end_index = (isize - 1) >> HPAGE_SHIFT;
      for (;;) {
            struct page *page;
            int nr, ret;

            /* nr is the maximum number of bytes to copy from this page */
            nr = HPAGE_SIZE;
            if (index >= end_index) {
                  if (index > end_index)
                        goto out;
                  nr = ((isize - 1) & ~HPAGE_MASK) + 1;
                  if (nr <= offset) {
                        goto out;
                  }
            }
            nr = nr - offset;

            /* Find the page */
            page = find_get_page(mapping, index);
            if (unlikely(page == NULL)) {
                  /*
                   * We have a HOLE, zero out the user-buffer for the
                   * length of the hole or request.
                   */
                  ret = len < nr ? len : nr;
                  if (clear_user(buf, ret))
                        ret = -EFAULT;
            } else {
                  /*
                   * We have the page, copy it to user space buffer.
                   */
                  ret = hugetlbfs_read_actor(page, offset, buf, len, nr);
            }
            if (ret < 0) {
                  if (retval == 0)
                        retval = ret;
                  if (page)
                        page_cache_release(page);
                  goto out;
            }

            offset += ret;
            retval += ret;
            len -= ret;
            index += offset >> HPAGE_SHIFT;
            offset &= ~HPAGE_MASK;

            if (page)
                  page_cache_release(page);

            /* short read or no more work */
            if ((ret != nr) || (len == 0))
                  break;
      }
out:
      *ppos = ((loff_t)index << HPAGE_SHIFT) + offset;
      mutex_unlock(&inode->i_mutex);
      return retval;
}

/*
 * Read a page. Again trivial. If it didn't already exist
 * in the page cache, it is zero-filled.
 */
static int hugetlbfs_readpage(struct file *file, struct page * page)
{
      unlock_page(page);
      return -EINVAL;
}

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 truncate_huge_page(struct page *page)
{
      cancel_dirty_page(page, /* No IO accounting for huge pages? */0);
      ClearPageUptodate(page);
      remove_from_page_cache(page);
      put_page(page);
}

static void truncate_hugepages(struct inode *inode, loff_t lstart)
{
      struct address_space *mapping = &inode->i_data;
      const pgoff_t start = lstart >> HPAGE_SHIFT;
      struct pagevec pvec;
      pgoff_t next;
      int i, freed = 0;

      pagevec_init(&pvec, 0);
      next = start;
      while (1) {
            if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
                  if (next == start)
                        break;
                  next = start;
                  continue;
            }

            for (i = 0; i < pagevec_count(&pvec); ++i) {
                  struct page *page = pvec.pages[i];

                  lock_page(page);
                  if (page->index > next)
                        next = page->index;
                  ++next;
                  truncate_huge_page(page);
                  unlock_page(page);
                  freed++;
            }
            huge_pagevec_release(&pvec);
      }
      BUG_ON(!lstart && mapping->nrpages);
      hugetlb_unreserve_pages(inode, start, freed);
}

static void hugetlbfs_delete_inode(struct inode *inode)
{
      truncate_hugepages(inode, 0);
      clear_inode(inode);
}

static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
{
      struct super_block *sb = inode->i_sb;

      if (!hlist_unhashed(&inode->i_hash)) {
            if (!(inode->i_state & (I_DIRTY|I_SYNC)))
                  list_move(&inode->i_list, &inode_unused);
            inodes_stat.nr_unused++;
            if (!sb || (sb->s_flags & MS_ACTIVE)) {
                  spin_unlock(&inode_lock);
                  return;
            }
            inode->i_state |= I_WILL_FREE;
            spin_unlock(&inode_lock);
            /*
             * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
             * in our backing_dev_info.
             */
            write_inode_now(inode, 1);
            spin_lock(&inode_lock);
            inode->i_state &= ~I_WILL_FREE;
            inodes_stat.nr_unused--;
            hlist_del_init(&inode->i_hash);
      }
      list_del_init(&inode->i_list);
      list_del_init(&inode->i_sb_list);
      inode->i_state |= I_FREEING;
      inodes_stat.nr_inodes--;
      spin_unlock(&inode_lock);
      truncate_hugepages(inode, 0);
      clear_inode(inode);
      destroy_inode(inode);
}

static void hugetlbfs_drop_inode(struct inode *inode)
{
      if (!inode->i_nlink)
            generic_delete_inode(inode);
      else
            hugetlbfs_forget_inode(inode);
}

static inline void
hugetlb_vmtruncate_list(struct prio_tree_root *root, pgoff_t pgoff)
{
      struct vm_area_struct *vma;
      struct prio_tree_iter iter;

      vma_prio_tree_foreach(vma, &iter, root, pgoff, ULONG_MAX) {
            unsigned long v_offset;

            /*
             * Can the expression below overflow on 32-bit arches?
             * No, because the prio_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 < pgoff)
                  v_offset = (pgoff - vma->vm_pgoff) << PAGE_SHIFT;
            else
                  v_offset = 0;

            __unmap_hugepage_range(vma,
                        vma->vm_start + v_offset, vma->vm_end);
      }
}

static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
{
      pgoff_t pgoff;
      struct address_space *mapping = inode->i_mapping;

      BUG_ON(offset & ~HPAGE_MASK);
      pgoff = offset >> PAGE_SHIFT;

      i_size_write(inode, offset);
      spin_lock(&mapping->i_mmap_lock);
      if (!prio_tree_empty(&mapping->i_mmap))
            hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
      spin_unlock(&mapping->i_mmap_lock);
      truncate_hugepages(inode, offset);
      return 0;
}

static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
{
      struct inode *inode = dentry->d_inode;
      int error;
      unsigned int ia_valid = attr->ia_valid;

      BUG_ON(!inode);

      error = inode_change_ok(inode, attr);
      if (error)
            goto out;

      if (ia_valid & ATTR_SIZE) {
            error = -EINVAL;
            if (!(attr->ia_size & ~HPAGE_MASK))
                  error = hugetlb_vmtruncate(inode, attr->ia_size);
            if (error)
                  goto out;
            attr->ia_valid &= ~ATTR_SIZE;
      }
      error = inode_setattr(inode, attr);
out:
      return error;
}

static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid, 
                              gid_t gid, int mode, dev_t dev)
{
      struct inode *inode;

      inode = new_inode(sb);
      if (inode) {
            struct hugetlbfs_inode_info *info;
            inode->i_mode = mode;
            inode->i_uid = uid;
            inode->i_gid = gid;
            inode->i_blocks = 0;
            inode->i_mapping->a_ops = &hugetlbfs_aops;
            inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
            inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
            INIT_LIST_HEAD(&inode->i_mapping->private_list);
            info = HUGETLBFS_I(inode);
            mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL);
            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;
                  break;
            }
      }
      return inode;
}

/*
 * File creation. Allocate an inode, and we're done..
 */
static int hugetlbfs_mknod(struct inode *dir,
                  struct dentry *dentry, int mode, dev_t dev)
{
      struct inode *inode;
      int error = -ENOSPC;
      gid_t gid;

      if (dir->i_mode & S_ISGID) {
            gid = dir->i_gid;
            if (S_ISDIR(mode))
                  mode |= S_ISGID;
      } else {
            gid = current->fsgid;
      }
      inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
      if (inode) {
            dir->i_ctime = dir->i_mtime = CURRENT_TIME;
            d_instantiate(dentry, inode);
            dget(dentry);     /* Extra count - pin the dentry in core */
            error = 0;
      }
      return error;
}

static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int 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, int mode, struct nameidata *nd)
{
      return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
}

static int hugetlbfs_symlink(struct inode *dir,
                  struct dentry *dentry, const char *symname)
{
      struct inode *inode;
      int error = -ENOSPC;
      gid_t gid;

      if (dir->i_mode & S_ISGID)
            gid = dir->i_gid;
      else
            gid = current->fsgid;

      inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
                              gid, 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;

      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_statfs(struct dentry *dentry, struct kstatfs *buf)
{
      struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);

      buf->f_type = HUGETLBFS_MAGIC;
      buf->f_bsize = HPAGE_SIZE;
      if (sbinfo) {
            spin_lock(&sbinfo->stat_lock);
            /* If no limits set, just report 0 for max/free/used
             * blocks, like simple_statfs() */
            if (sbinfo->max_blocks >= 0) {
                  buf->f_blocks = sbinfo->max_blocks;
                  buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
                  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;
            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;
      }
      return &p->vfs_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);
      kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
}

static const struct address_space_operations hugetlbfs_aops = {
      .readpage   = hugetlbfs_readpage,
      .write_begin      = hugetlbfs_write_begin,
      .write_end  = hugetlbfs_write_end,
      .set_page_dirty   = hugetlbfs_set_page_dirty,
};


static void init_once(struct kmem_cache *cachep, 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             = hugetlbfs_read,
      .mmap             = hugetlbfs_file_mmap,
      .fsync                  = simple_sync_file,
      .get_unmapped_area      = hugetlb_get_unmapped_area,
};

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,
};

static const struct inode_operations hugetlbfs_inode_operations = {
      .setattr    = hugetlbfs_setattr,
};

static const struct super_operations hugetlbfs_ops = {
      .alloc_inode    = hugetlbfs_alloc_inode,
      .destroy_inode  = hugetlbfs_destroy_inode,
      .statfs           = hugetlbfs_statfs,
      .delete_inode     = hugetlbfs_delete_inode,
      .drop_inode = hugetlbfs_drop_inode,
      .put_super  = hugetlbfs_put_super,
};

static int
hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
{
      char *p, *rest;
      substring_t args[MAX_OPT_ARGS];
      int option;

      if (!options)
            return 0;

      while ((p = strsep(&options, ",")) != NULL) {
            int token;
            if (!*p)
                  continue;

            token = match_token(p, tokens, args);
            switch (token) {
            case Opt_uid:
                  if (match_int(&args[0], &option))
                        goto bad_val;
                  pconfig->uid = option;
                  break;

            case Opt_gid:
                  if (match_int(&args[0], &option))
                        goto bad_val;
                  pconfig->gid = option;
                  break;

            case Opt_mode:
                  if (match_octal(&args[0], &option))
                        goto bad_val;
                  pconfig->mode = option & 0777U;
                  break;

            case Opt_size: {
                  unsigned long long size;
                  /* memparse() will accept a K/M/G without a digit */
                  if (!isdigit(*args[0].from))
                        goto bad_val;
                  size = memparse(args[0].from, &rest);
                  if (*rest == '%') {
                        size <<= HPAGE_SHIFT;
                        size *= max_huge_pages;
                        do_div(size, 100);
                  }
                  pconfig->nr_blocks = (size >> HPAGE_SHIFT);
                  break;
            }

            case Opt_nr_inodes:
                  /* memparse() will accept a K/M/G without a digit */
                  if (!isdigit(*args[0].from))
                        goto bad_val;
                  pconfig->nr_inodes = memparse(args[0].from, &rest);
                  break;

            default:
                  printk(KERN_ERR "hugetlbfs: Bad mount option: \"%s\"\n",
                         p);
                  return -EINVAL;
                  break;
            }
      }
      return 0;

bad_val:
      printk(KERN_ERR "hugetlbfs: Bad value '%s' for mount option '%s'\n",
             args[0].from, p);
      return 1;
}

static int
hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
{
      struct inode * inode;
      struct dentry * root;
      int ret;
      struct hugetlbfs_config config;
      struct hugetlbfs_sb_info *sbinfo;

      config.nr_blocks = -1; /* No limit on size by default */
      config.nr_inodes = -1; /* No limit on number of inodes by default */
      config.uid = current->fsuid;
      config.gid = current->fsgid;
      config.mode = 0755;
      ret = hugetlbfs_parse_options(data, &config);
      if (ret)
            return ret;

      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->max_blocks = config.nr_blocks;
      sbinfo->free_blocks = config.nr_blocks;
      sbinfo->max_inodes = config.nr_inodes;
      sbinfo->free_inodes = config.nr_inodes;
      sb->s_maxbytes = MAX_LFS_FILESIZE;
      sb->s_blocksize = HPAGE_SIZE;
      sb->s_blocksize_bits = HPAGE_SHIFT;
      sb->s_magic = HUGETLBFS_MAGIC;
      sb->s_op = &hugetlbfs_ops;
      sb->s_time_gran = 1;
      inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
                              S_IFDIR | config.mode, 0);
      if (!inode)
            goto out_free;

      root = d_alloc_root(inode);
      if (!root) {
            iput(inode);
            goto out_free;
      }
      sb->s_root = root;
      return 0;
out_free:
      kfree(sbinfo);
      return -ENOMEM;
}

int hugetlb_get_quota(struct address_space *mapping, long delta)
{
      int ret = 0;
      struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);

      if (sbinfo->free_blocks > -1) {
            spin_lock(&sbinfo->stat_lock);
            if (sbinfo->free_blocks - delta >= 0)
                  sbinfo->free_blocks -= delta;
            else
                  ret = -ENOMEM;
            spin_unlock(&sbinfo->stat_lock);
      }

      return ret;
}

void hugetlb_put_quota(struct address_space *mapping, long delta)
{
      struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);

      if (sbinfo->free_blocks > -1) {
            spin_lock(&sbinfo->stat_lock);
            sbinfo->free_blocks += delta;
            spin_unlock(&sbinfo->stat_lock);
      }
}

static int hugetlbfs_get_sb(struct file_system_type *fs_type,
      int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
      return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super, mnt);
}

static struct file_system_type hugetlbfs_fs_type = {
      .name       = "hugetlbfs",
      .get_sb           = hugetlbfs_get_sb,
      .kill_sb    = kill_litter_super,
};

static struct vfsmount *hugetlbfs_vfsmount;

static int can_do_hugetlb_shm(void)
{
      return likely(capable(CAP_IPC_LOCK) ||
                  in_group_p(sysctl_hugetlb_shm_group) ||
                  can_do_mlock());
}

struct file *hugetlb_file_setup(const char *name, size_t size)
{
      int error = -ENOMEM;
      struct file *file;
      struct inode *inode;
      struct dentry *dentry, *root;
      struct qstr quick_string;

      if (!hugetlbfs_vfsmount)
            return ERR_PTR(-ENOENT);

      if (!can_do_hugetlb_shm())
            return ERR_PTR(-EPERM);

      if (!user_shm_lock(size, current->user))
            return ERR_PTR(-ENOMEM);

      root = hugetlbfs_vfsmount->mnt_root;
      quick_string.name = name;
      quick_string.len = strlen(quick_string.name);
      quick_string.hash = 0;
      dentry = d_alloc(root, &quick_string);
      if (!dentry)
            goto out_shm_unlock;

      error = -ENOSPC;
      inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
                        current->fsgid, S_IFREG | S_IRWXUGO, 0);
      if (!inode)
            goto out_dentry;

      error = -ENOMEM;
      if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
            goto out_inode;

      d_instantiate(dentry, inode);
      inode->i_size = size;
      inode->i_nlink = 0;

      error = -ENFILE;
      file = alloc_file(hugetlbfs_vfsmount, dentry,
                  FMODE_WRITE | FMODE_READ,
                  &hugetlbfs_file_operations);
      if (!file)
            goto out_inode;

      return file;

out_inode:
      iput(inode);
out_dentry:
      dput(dentry);
out_shm_unlock:
      user_shm_unlock(size, current->user);
      return ERR_PTR(error);
}

static int __init init_hugetlbfs_fs(void)
{
      int error;
      struct vfsmount *vfsmount;

      error = bdi_init(&hugetlbfs_backing_dev_info);
      if (error)
            return error;

      hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
                              sizeof(struct hugetlbfs_inode_info),
                              0, 0, init_once);
      if (hugetlbfs_inode_cachep == NULL)
            goto out2;

      error = register_filesystem(&hugetlbfs_fs_type);
      if (error)
            goto out;

      vfsmount = kern_mount(&hugetlbfs_fs_type);

      if (!IS_ERR(vfsmount)) {
            hugetlbfs_vfsmount = vfsmount;
            return 0;
      }

      error = PTR_ERR(vfsmount);

 out:
      if (error)
            kmem_cache_destroy(hugetlbfs_inode_cachep);
 out2:
      bdi_destroy(&hugetlbfs_backing_dev_info);
      return error;
}

static void __exit exit_hugetlbfs_fs(void)
{
      kmem_cache_destroy(hugetlbfs_inode_cachep);
      unregister_filesystem(&hugetlbfs_fs_type);
      bdi_destroy(&hugetlbfs_backing_dev_info);
}

module_init(init_hugetlbfs_fs)
module_exit(exit_hugetlbfs_fs)

MODULE_LICENSE("GPL");

Generated by  Doxygen 1.6.0   Back to index