Release 4.7 fs/libfs.c

/*
 *      fs/libfs.c
 *      Library for filesystems writers.
 */

#include <linux/blkdev.h>
#include <linux/export.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/quotaops.h>
#include <linux/mutex.h>
#include <linux/namei.h>
#include <linux/exportfs.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h> /* sync_mapping_buffers */

#include <asm/uaccess.h>

#include "internal.h"



int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
		   struct kstat *stat)
{
	struct inode *inode = d_inode(dentry);
	generic_fillattr(inode, stat);
	stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
hirofumi ogawa
hirofumi ogawa
52
92.86%
1
33.33%
david howells
david howells
3
5.36%
1
33.33%
kirill a. shutemov
kirill a. shutemov
1
1.79%
1
33.33%
Total
56
100.00%
3
100.00%


EXPORT_SYMBOL(simple_getattr);



int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	buf->f_type = dentry->d_sb->s_magic;
	buf->f_bsize = PAGE_SIZE;
	buf->f_namelen = NAME_MAX;
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
33
82.50%
1
25.00%
david howells
david howells
5
12.50%
1
25.00%
kirill a. shutemov
kirill a. shutemov
1
2.50%
1
25.00%
andrew morton
andrew morton
1
2.50%
1
25.00%
Total
40
100.00%
4
100.00%


EXPORT_SYMBOL(simple_statfs);

/*
 * Retaining negative dentries for an in-memory filesystem just wastes
 * memory and lookup time: arrange for them to be deleted immediately.
 */


int always_delete_dentry(const struct dentry *dentry)
{
	return 1;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
hugh dickins
hugh dickins
12
85.71%
1
33.33%
al viro
al viro
1
7.14%
1
33.33%
nick piggin
nick piggin
1
7.14%
1
33.33%
Total
14
100.00%
3
100.00%


EXPORT_SYMBOL(always_delete_dentry);


const struct dentry_operations simple_dentry_operations = {
	.d_delete = always_delete_dentry,
};

EXPORT_SYMBOL(simple_dentry_operations);

/*
 * Lookup the data. This is trivial - if the dentry didn't already
 * exist, we know it is negative.  Set d_op to delete negative dentries.
 */


struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
	if (dentry->d_name.len > NAME_MAX)
		return ERR_PTR(-ENAMETOOLONG);
	if (!dentry->d_sb->s_d_op)
		d_set_d_op(dentry, &simple_dentry_operations);
	d_add(dentry, NULL);
	return NULL;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
39
60.00%
3
42.86%
andrew morton
andrew morton
17
26.15%
1
14.29%
nick piggin
nick piggin
4
6.15%
1
14.29%
hugh dickins
hugh dickins
4
6.15%
1
14.29%
trond myklebust
trond myklebust
1
1.54%
1
14.29%
Total
65
100.00%
7
100.00%


EXPORT_SYMBOL(simple_lookup);



int dcache_dir_open(struct inode *inode, struct file *file)
{
	file->private_data = d_alloc_cursor(file->f_path.dentry);

	return file->private_data ? 0 : -ENOMEM;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
35
92.11%
2
66.67%
josef 'jeff' sipek
josef 'jeff' sipek
3
7.89%
1
33.33%
Total
38
100.00%
3
100.00%


EXPORT_SYMBOL(dcache_dir_open);



int dcache_dir_close(struct inode *inode, struct file *file)
{
	dput(file->private_data);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
25
100.00%
1
100.00%
Total
25
100.00%
1
100.00%


EXPORT_SYMBOL(dcache_dir_close);

/* parent is locked at least shared */


static struct dentry *next_positive(struct dentry *parent,
				    struct list_head *from,
				    int count)
{
	unsigned *seq = &parent->d_inode->i_dir_seq, n;
	struct dentry *res;
	struct list_head *p;
	bool skipped;
	int i;

retry:
	i = count;
	skipped = false;
	n = smp_load_acquire(seq) & ~1;
	res = NULL;
	rcu_read_lock();
	for (p = from->next; p != &parent->d_subdirs; p = p->next) {
		struct dentry *d = list_entry(p, struct dentry, d_child);
		if (!simple_positive(d)) {
			skipped = true;
		} else if (!--i) {
			res = d;
			break;
		}
	}
	rcu_read_unlock();
	if (skipped) {
		smp_rmb();
		if (unlikely(*seq != n))
			goto retry;
	}
	return res;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
171
100.00%
2
100.00%
Total
171
100.00%
2
100.00%



static void move_cursor(struct dentry *cursor, struct list_head *after)
{
	struct dentry *parent = cursor->d_parent;
	unsigned n, *seq = &parent->d_inode->i_dir_seq;
	spin_lock(&parent->d_lock);
	for (;;) {
		n = *seq;
		if (!(n & 1) && cmpxchg(seq, n, n + 1) == n)
			break;
		cpu_relax();
	}
	__list_del(cursor->d_child.prev, cursor->d_child.next);
	if (after)
		list_add(&cursor->d_child, after);
	else
		list_add_tail(&cursor->d_child, &parent->d_subdirs);
	smp_store_release(seq, n + 2);
	spin_unlock(&parent->d_lock);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
144
100.00%
2
100.00%
Total
144
100.00%
2
100.00%



loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
{
	struct dentry *dentry = file->f_path.dentry;
	switch (whence) {
		case 1:
			offset += file->f_pos;
		case 0:
			if (offset >= 0)
				break;
		default:
			return -EINVAL;
	}
	if (offset != file->f_pos) {
		file->f_pos = offset;
		if (file->f_pos >= 2) {
			struct dentry *cursor = file->private_data;
			struct dentry *to;
			loff_t n = file->f_pos - 2;

			inode_lock_shared(dentry->d_inode);
			to = next_positive(dentry, &dentry->d_subdirs, n);
			move_cursor(cursor, to ? &to->d_child : NULL);
			inode_unlock_shared(dentry->d_inode);
		}
	}
	return offset;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
135
89.40%
3
50.00%
nick piggin
nick piggin
9
5.96%
1
16.67%
josef 'jeff' sipek
josef 'jeff' sipek
5
3.31%
1
16.67%
andrew morton
andrew morton
2
1.32%
1
16.67%
Total
151
100.00%
6
100.00%


EXPORT_SYMBOL(dcache_dir_lseek);

/* Relationship between i_mode and the DT_xxx types */


static inline unsigned char dt_type(struct inode *inode)
{
	return (inode->i_mode >> 12) & 15;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
linus torvalds
linus torvalds
24
100.00%
1
100.00%
Total
24
100.00%
1
100.00%

/*
 * Directory is locked and all positive dentries in it are safe, since
 * for ramfs-type trees they can't go away without unlink() or rmdir(),
 * both impossible due to the lock on directory.
 */



int dcache_readdir(struct file *file, struct dir_context *ctx)
{
	struct dentry *dentry = file->f_path.dentry;
	struct dentry *cursor = file->private_data;
	struct list_head *p = &cursor->d_child;
	struct dentry *next;
	bool moved = false;

	if (!dir_emit_dots(file, ctx))
		return 0;

	if (ctx->pos == 2)
		p = &dentry->d_subdirs;
	while ((next = next_positive(dentry, p, 1)) != NULL) {
		if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
			      d_inode(next)->i_ino, dt_type(d_inode(next))))
			break;
		moved = true;
		p = &next->d_child;
		ctx->pos++;
	}
	if (moved)
		move_cursor(cursor, p);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
152
90.48%
4
44.44%
david howells
david howells
6
3.57%
1
11.11%
linus torvalds
linus torvalds
4
2.38%
1
11.11%
josef 'jeff' sipek
josef 'jeff' sipek
3
1.79%
1
11.11%
nick piggin
nick piggin
3
1.79%
2
22.22%
Total
168
100.00%
9
100.00%


EXPORT_SYMBOL(dcache_readdir);



ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
{
	return -EISDIR;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
25
96.15%
1
50.00%
linus torvalds
linus torvalds
1
3.85%
1
50.00%
Total
26
100.00%
2
100.00%


EXPORT_SYMBOL(generic_read_dir);


const struct file_operations simple_dir_operations = {
	.open		= dcache_dir_open,
	.release	= dcache_dir_close,
	.llseek		= dcache_dir_lseek,
	.read		= generic_read_dir,
	.iterate_shared	= dcache_readdir,
	.fsync		= noop_fsync,
};

EXPORT_SYMBOL(simple_dir_operations);


const struct inode_operations simple_dir_inode_operations = {
	.lookup		= simple_lookup,
};

EXPORT_SYMBOL(simple_dir_inode_operations);


static const struct super_operations simple_super_operations = {
	.statfs		= simple_statfs,
};

/*
 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
 * will never be mountable)
 */


struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
	const struct super_operations *ops,
	const struct dentry_operations *dops, unsigned long magic)
{
	struct super_block *s;
	struct dentry *dentry;
	struct inode *root;
	struct qstr d_name = QSTR_INIT(name, strlen(name));

	s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);
	if (IS_ERR(s))
		return ERR_CAST(s);

	s->s_maxbytes = MAX_LFS_FILESIZE;
	s->s_blocksize = PAGE_SIZE;
	s->s_blocksize_bits = PAGE_SHIFT;
	s->s_magic = magic;
	s->s_op = ops ? ops : &simple_super_operations;
	s->s_time_gran = 1;
	root = new_inode(s);
	if (!root)
		goto Enomem;
	/*
         * since this is the first inode, make it number 1. New inodes created
         * after this must take care not to collide with it (by passing
         * max_reserved of 1 to iunique).
         */
	root->i_ino = 1;
	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
	dentry = __d_alloc(s, &d_name);
	if (!dentry) {
		iput(root);
		goto Enomem;
	}
	d_instantiate(dentry, root);
	s->s_root = dentry;
	s->s_d_op = dops;
	s->s_flags |= MS_ACTIVE;
	return dget(s->s_root);

Enomem:
	deactivate_locked_super(s);
	return ERR_PTR(-ENOMEM);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
206
83.06%
5
35.71%
david howells
david howells
19
7.66%
2
14.29%
jeff layton
jeff layton
8
3.23%
2
14.29%
andi kleen
andi kleen
6
2.42%
1
7.14%
linus torvalds
linus torvalds
5
2.02%
1
7.14%
alex nixon
alex nixon
2
0.81%
1
7.14%
hugh dickins
hugh dickins
1
0.40%
1
7.14%
josef 'jeff' sipek
josef 'jeff' sipek
1
0.40%
1
7.14%
Total
248
100.00%
14
100.00%


EXPORT_SYMBOL(mount_pseudo);



int simple_open(struct inode *inode, struct file *file)
{
	if (inode->i_private)
		file->private_data = inode->i_private;
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
stephen boyd
stephen boyd
32
100.00%
1
100.00%
Total
32
100.00%
1
100.00%


EXPORT_SYMBOL(simple_open);



int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = d_inode(old_dentry);

	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	inc_nlink(inode);
	ihold(inode);
	dget(dentry);
	d_instantiate(dentry, inode);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
62
89.86%
2
40.00%
david howells
david howells
3
4.35%
1
20.00%
dave hansen
dave hansen
3
4.35%
1
20.00%
al viro
al viro
1
1.45%
1
20.00%
Total
69
100.00%
5
100.00%


EXPORT_SYMBOL(simple_link);



int simple_empty(struct dentry *dentry)
{
	struct dentry *child;
	int ret = 0;

	spin_lock(&dentry->d_lock);
	list_for_each_entry(child, &dentry->d_subdirs, d_child) {
		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
		if (simple_positive(child)) {
			spin_unlock(&child->d_lock);
			goto out;
		}
		spin_unlock(&child->d_lock);
	}
	ret = 1;
out:
	spin_unlock(&dentry->d_lock);
	return ret;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
52
55.91%
1
25.00%
nick piggin
nick piggin
40
43.01%
2
50.00%
al viro
al viro
1
1.08%
1
25.00%
Total
93
100.00%
4
100.00%


EXPORT_SYMBOL(simple_empty);



int simple_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);

	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	drop_nlink(inode);
	dput(dentry);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
46
88.46%
2
50.00%
david howells
david howells
3
5.77%
1
25.00%
dave hansen
dave hansen
3
5.77%
1
25.00%
Total
52
100.00%
4
100.00%


EXPORT_SYMBOL(simple_unlink);



int simple_rmdir(struct inode *dir, struct dentry *dentry)
{
	if (!simple_empty(dentry))
		return -ENOTEMPTY;

	drop_nlink(d_inode(dentry));
	simple_unlink(dir, dentry);
	drop_nlink(dir);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
41
82.00%
1
33.33%
dave hansen
dave hansen
6
12.00%
1
33.33%
david howells
david howells
3
6.00%
1
33.33%
Total
50
100.00%
3
100.00%


EXPORT_SYMBOL(simple_rmdir);



int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
		struct inode *new_dir, struct dentry *new_dentry)
{
	struct inode *inode = d_inode(old_dentry);
	int they_are_dirs = d_is_dir(old_dentry);

	if (!simple_empty(new_dentry))
		return -ENOTEMPTY;

	if (d_really_is_positive(new_dentry)) {
		simple_unlink(new_dir, new_dentry);
		if (they_are_dirs) {
			drop_nlink(d_inode(new_dentry));
			drop_nlink(old_dir);
		}
	} else if (they_are_dirs) {
		drop_nlink(old_dir);
		inc_nlink(new_dir);
	}

	old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
		new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;

	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
106
80.30%
3
37.50%
david howells
david howells
10
7.58%
2
25.00%
dave hansen
dave hansen
9
6.82%
2
25.00%
al viro
al viro
7
5.30%
1
12.50%
Total
132
100.00%
8
100.00%


EXPORT_SYMBOL(simple_rename);

/**
 * simple_setattr - setattr for simple filesystem
 * @dentry: dentry
 * @iattr: iattr structure
 *
 * Returns 0 on success, -error on failure.
 *
 * simple_setattr is a simple ->setattr implementation without a proper
 * implementation of size changes.
 *
 * It can either be used for in-memory filesystems or special files
 * on simple regular filesystems.  Anything that needs to change on-disk
 * or wire state on size changes needs its own setattr method.
 */


int simple_setattr(struct dentry *dentry, struct iattr *iattr)
{
	struct inode *inode = d_inode(dentry);
	int error;

	error = inode_change_ok(inode, iattr);
	if (error)
		return error;

	if (iattr->ia_valid & ATTR_SIZE)
		truncate_setsize(inode, iattr->ia_size);
	setattr_copy(inode, iattr);
	mark_inode_dirty(inode);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
nick piggin
nick piggin
65
85.53%
1
20.00%
christoph hellwig
christoph hellwig
8
10.53%
3
60.00%
david howells
david howells
3
3.95%
1
20.00%
Total
76
100.00%
5
100.00%


EXPORT_SYMBOL(simple_setattr);



int simple_readpage(struct file *file, struct page *page)
{
	clear_highpage(page);
	flush_dcache_page(page);
	SetPageUptodate(page);
	unlock_page(page);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
andrew morton
andrew morton
37
97.37%
1
50.00%
pekka j enberg
pekka j enberg
1
2.63%
1
50.00%
Total
38
100.00%
2
100.00%


EXPORT_SYMBOL(simple_readpage);



int simple_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
{
	struct page *page;
	pgoff_t index;

	index = pos >> PAGE_SHIFT;

	page = grab_cache_page_write_begin(mapping, index, flags);
	if (!page)
		return -ENOMEM;

	*pagep = page;

	if (!PageUptodate(page) && (len != PAGE_SIZE)) {
		unsigned from = pos & (PAGE_SIZE - 1);

		zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
	}
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
nick piggin
nick piggin
83
69.75%
2
50.00%
boaz harrosh
boaz harrosh
32
26.89%
1
25.00%
kirill a. shutemov
kirill a. shutemov
4
3.36%
1
25.00%
Total
119
100.00%
4
100.00%


EXPORT_SYMBOL(simple_write_begin);

/**
 * simple_write_end - .write_end helper for non-block-device FSes
 * @available: See .write_end of address_space_operations
 * @file:               "
 * @mapping:            "
 * @pos:                "
 * @len:                "
 * @copied:             "
 * @page:               "
 * @fsdata:             "
 *
 * simple_write_end does the minimum needed for updating a page after writing is
 * done. It has the same API signature as the .write_end of
 * address_space_operations vector. So it can just be set onto .write_end for
 * FSes that don't need any other processing. i_mutex is assumed to be held.
 * Block based filesystems should use generic_write_end().
 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
 * is not called, so a filesystem that actually does store data in .write_inode
 * should extend on what's done here with a call to mark_inode_dirty() in the
 * case that i_size has changed.
 */


int simple_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
{
	struct inode *inode = page->mapping->host;
	loff_t last_pos = pos + copied;

	/* zero the stale part of the page if we did a short copy */
	if (copied < len) {
		unsigned from = pos & (PAGE_SIZE - 1);

		zero_user(page, from + copied, len - copied);
	}

	if (!PageUptodate(page))
		SetPageUptodate(page);
	/*
         * No need to use i_size_read() here, the i_size
         * cannot change under us because we hold the i_mutex.
         */
	if (last_pos > inode->i_size)
		i_size_write(inode, last_pos);

	set_page_dirty(page);
	unlock_page(page);
	put_page(page);

	return copied;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
nick piggin
nick piggin
81
61.83%
1
33.33%
boaz harrosh
boaz harrosh
48
36.64%
1
33.33%
kirill a. shutemov
kirill a. shutemov
2
1.53%
1
33.33%
Total
131
100.00%
3
100.00%


EXPORT_SYMBOL(simple_write_end);

/*
 * the inodes created here are not hashed. If you use iunique to generate
 * unique inode values later for this filesystem, then you must take care
 * to pass it an appropriate max_reserved value to avoid collisions.
 */


int simple_fill_super(struct super_block *s, unsigned long magic,
		      struct tree_descr *files)
{
	struct inode *inode;
	struct dentry *root;
	struct dentry *dentry;
	int i;

	s->s_blocksize = PAGE_SIZE;
	s->s_blocksize_bits = PAGE_SHIFT;
	s->s_magic = magic;
	s->s_op = &simple_super_operations;
	s->s_time_gran = 1;

	inode = new_inode(s);
	if (!inode)
		return -ENOMEM;
	/*
         * because the root inode is 1, the files array must not contain an
         * entry at index 1
         */
	inode->i_ino = 1;
	inode->i_mode = S_IFDIR | 0755;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	set_nlink(inode, 2);
	root = d_make_root(inode);
	if (!root)
		return -ENOMEM;
	for (i = 0; !files->name || files->name[0]; i++, files++) {
		if (!files->name)
			continue;

		/* warn if it tries to conflict with the root inode */
		if (unlikely(i == 1))
			printk(KERN_WARNING "%s: %s passed in a files array"
				"with an index of 1!\n", __func__,
				s->s_type->name);

		dentry = d_alloc_name(root, files->name);
		if (!dentry)
			goto out;
		inode = new_inode(s);
		if (!inode) {
			dput(dentry);
			goto out;
		}
		inode->i_mode = S_IFREG | files->mode;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
		inode->i_fop = files->ops;
		inode->i_ino = i;
		d_add(dentry, inode);
	}
	s->s_root = root;
	return 0;
out:
	d_genocide(root);
	shrink_dcache_parent(root);
	dput(root);
	return -ENOMEM;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
265
81.54%
3
25.00%
jeff layton
jeff layton
32
9.85%
1
8.33%
konstantin khlebnikov
konstantin khlebnikov
7
2.15%
1
8.33%
andi kleen
andi kleen
6
1.85%
1
8.33%
miklos szeredi
miklos szeredi
4
1.23%
1
8.33%
vincent hanquez
vincent hanquez
3
0.92%
1
8.33%
james morris
james morris
3
0.92%
1
8.33%
kirill a. shutemov
kirill a. shutemov
2
0.62%
1
8.33%
roberto sassu
roberto sassu
2
0.62%
1
8.33%
hugh dickins
hugh dickins
1
0.31%
1
8.33%
Total
325
100.00%
12
100.00%


EXPORT_SYMBOL(simple_fill_super);

static DEFINE_SPINLOCK(pin_fs_lock);



int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
{
	struct vfsmount *mnt = NULL;
	spin_lock(&pin_fs_lock);
	if (unlikely(!*mount)) {
		spin_unlock(&pin_fs_lock);
		mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
		if (IS_ERR(mnt))
			return PTR_ERR(mnt);
		spin_lock(&pin_fs_lock);
		if (!*mount)
			*mount = mnt;
	}
	mntget(*mount);
	++*count;
	spin_unlock(&pin_fs_lock);
	mntput(mnt);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
112
94.12%
2
66.67%
trond myklebust
trond myklebust
7
5.88%
1
33.33%
Total
119
100.00%
3
100.00%


EXPORT_SYMBOL(simple_pin_fs);



void simple_release_fs(struct vfsmount **mount, int *count)
{
	struct vfsmount *mnt;
	spin_lock(&pin_fs_lock);
	mnt = *mount;
	if (!--*count)
		*mount = NULL;
	spin_unlock(&pin_fs_lock);
	mntput(mnt);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
54
100.00%
1
100.00%
Total
54
100.00%
1
100.00%


EXPORT_SYMBOL(simple_release_fs);

/**
 * simple_read_from_buffer - copy data from the buffer to user space
 * @to: the user space buffer to read to
 * @count: the maximum number of bytes to read
 * @ppos: the current position in the buffer
 * @from: the buffer to read from
 * @available: the size of the buffer
 *
 * The simple_read_from_buffer() function reads up to @count bytes from the
 * buffer @from at offset @ppos into the user space address starting at @to.
 *
 * On success, the number of bytes read is returned and the offset @ppos is
 * advanced by this number, or negative value is returned on error.
 **/


ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
				const void *from, size_t available)
{
	loff_t pos = *ppos;
	size_t ret;

	if (pos < 0)
		return -EINVAL;
	if (pos >= available || !count)
		return 0;
	if (count > available - pos)
		count = available - pos;
	ret = copy_to_user(to, from + pos, count);
	if (ret == count)
		return -EFAULT;
	count -= ret;
	*ppos = pos + count;
	return count;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
al viro
al viro
88
82.24%
1
33.33%
steven rostedt
steven rostedt
18
16.82%
1
33.33%
linus torvalds
linus torvalds
1
0.93%
1
33.33%
Total
107
100.00%
3
100.00%


EXPORT_SYMBOL(simple_read_from_buffer);

/**
 * simple_write_to_buffer - copy data from user space to the buffer
 * @to: the buffer to write to
 * @available: the size of the buffer
 * @ppos: the current position in the buffer
 * @from: the user space buffer to read from
 * @count: the maximum number of bytes to read
 *
 * The simple_write_to_buffer() function reads up to @count bytes from the user
 * space address starting at @from into the buffer @to at offset @ppos.
 *
 * On success, the number of bytes written is returned and the offset @ppos is
 * advanced by this number, or negative value is returned on error.
 **/


ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
		const void __user *from, size_t count)
{
	loff_t pos = *ppos;
	size_t res;

	if (pos < 0)
		return -EINVAL;
	if (pos >= available || !count)
		return 0;
	if (count > available - pos)
		count = available - pos;
	res = copy_from_user(to + pos, from, count);
	if (res == count)
		return -EFAULT;
	count -= res;
	*ppos =