path: root/fs/affs/file.c

/*
 *  linux/fs/affs/file.c
 *
 *  (c) 1996  Hans-Joachim Widmaier - Rewritten
 *
 *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
 *
 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
 *
 *  (C) 1991  Linus Torvalds - minix filesystem
 *
 *  affs regular file handling primitives
 */

#include "affs.h"

#if PAGE_SIZE < 4096
#error PAGE_SIZE must be at least 4096
#endif

static int affs_grow_extcache(struct inode *inode, u32 lc_idx);
static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
static int affs_file_open(struct inode *inode, struct file *filp);
static int affs_file_release(struct inode *inode, struct file *filp);

const struct file_operations affs_file_operations = {
	.llseek		= generic_file_llseek,
	.read		= do_sync_read,
	.aio_read	= generic_file_aio_read,
	.write		= do_sync_write,
	.aio_write	= generic_file_aio_write,
	.mmap		= generic_file_mmap,
	.open		= affs_file_open,
	.release	= affs_file_release,
	.fsync		= file_fsync,
	.splice_read	= generic_file_splice_read,
};

const struct inode_operations affs_file_inode_operations = {
	.truncate	= affs_truncate,
	.setattr	= affs_notify_change,
};

static int
affs_file_open(struct inode *inode, struct file *filp)
{
	if (atomic_read(&filp->f_count) != 1)
		return 0;
	pr_debug("AFFS: open(%d)\n", AFFS_I(inode)->i_opencnt);
	AFFS_I(inode)->i_opencnt++;
	return 0;
}

static int
affs_file_release(struct inode *inode, struct file *filp)
{
	if (atomic_read(&filp->f_count) != 0)
		return 0;
	pr_debug("AFFS: release(%d)\n", AFFS_I(inode)->i_opencnt);
	AFFS_I(inode)->i_opencnt--;
	if (!AFFS_I(inode)->i_opencnt)
		affs_free_prealloc(inode);

	return 0;
}

static int
affs_grow_extcache(struct inode *inode, u32 lc_idx)
{
	struct super_block	*sb = inode->i_sb;
	struct buffer_head	*bh;
	u32 lc_max;
	int i, j, key;

	if (!AFFS_I(inode)->i_lc) {
		char *ptr = (char *)get_zeroed_page(GFP_NOFS);
		if (!ptr)
			return -ENOMEM;
		AFFS_I(inode)->i_lc = (u32 *)ptr;
		AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
	}

	lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;

	if (AFFS_I(inode)->i_extcnt > lc_max) {
		u32 lc_shift, lc_mask, tmp, off;

		/* need to recalculate linear cache, start from old size */
		lc_shift = AFFS_I(inode)->i_lc_shift;
		tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
		for (; tmp; tmp >>= 1)
			lc_shift++;
		lc_mask = (1 << lc_shift) - 1;

		/* fix idx and old size to new shift */
		lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
		AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);

		/* first shrink old cache to make more space */
		off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
		for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
			AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];

		AFFS_I(inode)->i_lc_shift = lc_shift;
		AFFS_I(inode)->i_lc_mask = lc_mask;
	}

	/* fill cache to the needed index */
	i = AFFS_I(inode)->i_lc_size;
	AFFS_I(inode)->i_lc_size = lc_idx + 1;
	for (; i <= lc_idx; i++) {
		if (!i) {
			AFFS_I(inode)->i_lc[0] = inode->i_ino;
			continue;
		}
		key = AFFS_I(inode)->i_lc[i - 1];
		j = AFFS_I(inode)->i_lc_mask + 1;
		// unlock cache
		for (; j > 0; j--) {