667 lines
16 KiB
C
667 lines
16 KiB
C
/*
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* Copyright (C) 2004, OGAWA Hirofumi
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* Released under GPL v2.
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/msdos_fs.h>
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#include <linux/blkdev.h>
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struct fatent_operations {
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void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
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void (*ent_set_ptr)(struct fat_entry *, int);
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int (*ent_bread)(struct super_block *, struct fat_entry *,
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int, sector_t);
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int (*ent_get)(struct fat_entry *);
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void (*ent_put)(struct fat_entry *, int);
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int (*ent_next)(struct fat_entry *);
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};
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static DEFINE_SPINLOCK(fat12_entry_lock);
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static void fat12_ent_blocknr(struct super_block *sb, int entry,
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int *offset, sector_t *blocknr)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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int bytes = entry + (entry >> 1);
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WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
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*offset = bytes & (sb->s_blocksize - 1);
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*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
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}
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static void fat_ent_blocknr(struct super_block *sb, int entry,
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int *offset, sector_t *blocknr)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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int bytes = (entry << sbi->fatent_shift);
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WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
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*offset = bytes & (sb->s_blocksize - 1);
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*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
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}
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static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
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{
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struct buffer_head **bhs = fatent->bhs;
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if (fatent->nr_bhs == 1) {
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WARN_ON(offset >= (bhs[0]->b_size - 1));
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fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
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fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
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} else {
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WARN_ON(offset != (bhs[0]->b_size - 1));
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fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
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fatent->u.ent12_p[1] = bhs[1]->b_data;
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}
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}
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static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
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{
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WARN_ON(offset & (2 - 1));
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fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
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}
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static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
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{
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WARN_ON(offset & (4 - 1));
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fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
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}
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static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
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int offset, sector_t blocknr)
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{
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struct buffer_head **bhs = fatent->bhs;
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WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
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bhs[0] = sb_bread(sb, blocknr);
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if (!bhs[0])
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goto err;
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if ((offset + 1) < sb->s_blocksize)
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fatent->nr_bhs = 1;
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else {
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/* This entry is block boundary, it needs the next block */
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blocknr++;
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bhs[1] = sb_bread(sb, blocknr);
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if (!bhs[1])
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goto err_brelse;
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fatent->nr_bhs = 2;
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}
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fat12_ent_set_ptr(fatent, offset);
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return 0;
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err_brelse:
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brelse(bhs[0]);
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err:
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printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
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(unsigned long long)blocknr);
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return -EIO;
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}
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static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
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int offset, sector_t blocknr)
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{
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struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
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WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
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fatent->bhs[0] = sb_bread(sb, blocknr);
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if (!fatent->bhs[0]) {
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printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
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(unsigned long long)blocknr);
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return -EIO;
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}
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fatent->nr_bhs = 1;
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ops->ent_set_ptr(fatent, offset);
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return 0;
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}
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static int fat12_ent_get(struct fat_entry *fatent)
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{
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u8 **ent12_p = fatent->u.ent12_p;
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int next;
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spin_lock(&fat12_entry_lock);
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if (fatent->entry & 1)
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next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
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else
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next = (*ent12_p[1] << 8) | *ent12_p[0];
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spin_unlock(&fat12_entry_lock);
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next &= 0x0fff;
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if (next >= BAD_FAT12)
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next = FAT_ENT_EOF;
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return next;
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}
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static int fat16_ent_get(struct fat_entry *fatent)
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{
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int next = le16_to_cpu(*fatent->u.ent16_p);
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WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
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if (next >= BAD_FAT16)
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next = FAT_ENT_EOF;
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return next;
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}
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static int fat32_ent_get(struct fat_entry *fatent)
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{
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int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
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WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
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if (next >= BAD_FAT32)
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next = FAT_ENT_EOF;
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return next;
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}
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static void fat12_ent_put(struct fat_entry *fatent, int new)
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{
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u8 **ent12_p = fatent->u.ent12_p;
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if (new == FAT_ENT_EOF)
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new = EOF_FAT12;
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spin_lock(&fat12_entry_lock);
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if (fatent->entry & 1) {
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*ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
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*ent12_p[1] = new >> 4;
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} else {
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*ent12_p[0] = new & 0xff;
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*ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
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}
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spin_unlock(&fat12_entry_lock);
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mark_buffer_dirty(fatent->bhs[0]);
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if (fatent->nr_bhs == 2)
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mark_buffer_dirty(fatent->bhs[1]);
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}
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static void fat16_ent_put(struct fat_entry *fatent, int new)
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{
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if (new == FAT_ENT_EOF)
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new = EOF_FAT16;
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*fatent->u.ent16_p = cpu_to_le16(new);
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mark_buffer_dirty(fatent->bhs[0]);
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}
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static void fat32_ent_put(struct fat_entry *fatent, int new)
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{
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if (new == FAT_ENT_EOF)
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new = EOF_FAT32;
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WARN_ON(new & 0xf0000000);
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new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
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*fatent->u.ent32_p = cpu_to_le32(new);
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mark_buffer_dirty(fatent->bhs[0]);
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}
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static int fat12_ent_next(struct fat_entry *fatent)
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{
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u8 **ent12_p = fatent->u.ent12_p;
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struct buffer_head **bhs = fatent->bhs;
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u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
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fatent->entry++;
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if (fatent->nr_bhs == 1) {
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WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
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WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
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if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
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ent12_p[0] = nextp - 1;
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ent12_p[1] = nextp;
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return 1;
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}
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} else {
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WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
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WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
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ent12_p[0] = nextp - 1;
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ent12_p[1] = nextp;
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brelse(bhs[0]);
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bhs[0] = bhs[1];
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fatent->nr_bhs = 1;
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return 1;
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}
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ent12_p[0] = NULL;
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ent12_p[1] = NULL;
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return 0;
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}
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static int fat16_ent_next(struct fat_entry *fatent)
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{
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const struct buffer_head *bh = fatent->bhs[0];
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fatent->entry++;
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if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
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fatent->u.ent16_p++;
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return 1;
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}
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fatent->u.ent16_p = NULL;
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return 0;
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}
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static int fat32_ent_next(struct fat_entry *fatent)
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{
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const struct buffer_head *bh = fatent->bhs[0];
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fatent->entry++;
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if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
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fatent->u.ent32_p++;
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return 1;
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}
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fatent->u.ent32_p = NULL;
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return 0;
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}
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static struct fatent_operations fat12_ops = {
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.ent_blocknr = fat12_ent_blocknr,
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.ent_set_ptr = fat12_ent_set_ptr,
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.ent_bread = fat12_ent_bread,
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.ent_get = fat12_ent_get,
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.ent_put = fat12_ent_put,
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.ent_next = fat12_ent_next,
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};
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static struct fatent_operations fat16_ops = {
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.ent_blocknr = fat_ent_blocknr,
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.ent_set_ptr = fat16_ent_set_ptr,
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.ent_bread = fat_ent_bread,
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.ent_get = fat16_ent_get,
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.ent_put = fat16_ent_put,
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.ent_next = fat16_ent_next,
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};
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static struct fatent_operations fat32_ops = {
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.ent_blocknr = fat_ent_blocknr,
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.ent_set_ptr = fat32_ent_set_ptr,
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.ent_bread = fat_ent_bread,
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.ent_get = fat32_ent_get,
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.ent_put = fat32_ent_put,
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.ent_next = fat32_ent_next,
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};
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static inline void lock_fat(struct msdos_sb_info *sbi)
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{
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mutex_lock(&sbi->fat_lock);
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}
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static inline void unlock_fat(struct msdos_sb_info *sbi)
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{
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mutex_unlock(&sbi->fat_lock);
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}
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void fat_ent_access_init(struct super_block *sb)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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mutex_init(&sbi->fat_lock);
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switch (sbi->fat_bits) {
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case 32:
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sbi->fatent_shift = 2;
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sbi->fatent_ops = &fat32_ops;
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break;
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case 16:
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sbi->fatent_shift = 1;
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sbi->fatent_ops = &fat16_ops;
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break;
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case 12:
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sbi->fatent_shift = -1;
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sbi->fatent_ops = &fat12_ops;
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break;
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}
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}
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static inline int fat_ent_update_ptr(struct super_block *sb,
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struct fat_entry *fatent,
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int offset, sector_t blocknr)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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struct fatent_operations *ops = sbi->fatent_ops;
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struct buffer_head **bhs = fatent->bhs;
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/* Is this fatent's blocks including this entry? */
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if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
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return 0;
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/* Does this entry need the next block? */
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if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
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if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
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return 0;
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}
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ops->ent_set_ptr(fatent, offset);
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return 1;
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}
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int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
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{
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struct super_block *sb = inode->i_sb;
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struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
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struct fatent_operations *ops = sbi->fatent_ops;
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int err, offset;
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sector_t blocknr;
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if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
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fatent_brelse(fatent);
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fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
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return -EIO;
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}
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fatent_set_entry(fatent, entry);
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ops->ent_blocknr(sb, entry, &offset, &blocknr);
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if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
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fatent_brelse(fatent);
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err = ops->ent_bread(sb, fatent, offset, blocknr);
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if (err)
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return err;
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}
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return ops->ent_get(fatent);
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}
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/* FIXME: We can write the blocks as more big chunk. */
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static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
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int nr_bhs)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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struct buffer_head *c_bh;
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int err, n, copy;
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err = 0;
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for (copy = 1; copy < sbi->fats; copy++) {
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sector_t backup_fat = sbi->fat_length * copy;
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for (n = 0; n < nr_bhs; n++) {
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c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
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if (!c_bh) {
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err = -ENOMEM;
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goto error;
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}
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memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
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set_buffer_uptodate(c_bh);
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mark_buffer_dirty(c_bh);
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if (sb->s_flags & MS_SYNCHRONOUS)
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err = sync_dirty_buffer(c_bh);
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brelse(c_bh);
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if (err)
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goto error;
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}
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}
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error:
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return err;
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}
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int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
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int new, int wait)
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{
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struct super_block *sb = inode->i_sb;
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struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
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int err;
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ops->ent_put(fatent, new);
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if (wait) {
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err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
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if (err)
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return err;
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}
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return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
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}
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static inline int fat_ent_next(struct msdos_sb_info *sbi,
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struct fat_entry *fatent)
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{
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if (sbi->fatent_ops->ent_next(fatent)) {
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if (fatent->entry < sbi->max_cluster)
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return 1;
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}
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return 0;
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}
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static inline int fat_ent_read_block(struct super_block *sb,
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struct fat_entry *fatent)
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{
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struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
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sector_t blocknr;
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int offset;
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fatent_brelse(fatent);
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ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
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return ops->ent_bread(sb, fatent, offset, blocknr);
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}
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static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
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struct fat_entry *fatent)
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{
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int n, i;
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for (n = 0; n < fatent->nr_bhs; n++) {
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for (i = 0; i < *nr_bhs; i++) {
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if (fatent->bhs[n] == bhs[i])
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break;
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}
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if (i == *nr_bhs) {
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get_bh(fatent->bhs[n]);
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bhs[i] = fatent->bhs[n];
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(*nr_bhs)++;
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}
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}
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}
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int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
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{
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struct super_block *sb = inode->i_sb;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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struct fatent_operations *ops = sbi->fatent_ops;
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struct fat_entry fatent, prev_ent;
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struct buffer_head *bhs[MAX_BUF_PER_PAGE];
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int i, count, err, nr_bhs, idx_clus;
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BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
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lock_fat(sbi);
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if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
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sbi->free_clusters < nr_cluster) {
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unlock_fat(sbi);
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return -ENOSPC;
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}
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err = nr_bhs = idx_clus = 0;
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count = FAT_START_ENT;
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fatent_init(&prev_ent);
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fatent_init(&fatent);
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fatent_set_entry(&fatent, sbi->prev_free + 1);
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while (count < sbi->max_cluster) {
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if (fatent.entry >= sbi->max_cluster)
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fatent.entry = FAT_START_ENT;
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fatent_set_entry(&fatent, fatent.entry);
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err = fat_ent_read_block(sb, &fatent);
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if (err)
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goto out;
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/* Find the free entries in a block */
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do {
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if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
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int entry = fatent.entry;
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|
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/* make the cluster chain */
|
|
ops->ent_put(&fatent, FAT_ENT_EOF);
|
|
if (prev_ent.nr_bhs)
|
|
ops->ent_put(&prev_ent, entry);
|
|
|
|
fat_collect_bhs(bhs, &nr_bhs, &fatent);
|
|
|
|
sbi->prev_free = entry;
|
|
if (sbi->free_clusters != -1)
|
|
sbi->free_clusters--;
|
|
sb->s_dirt = 1;
|
|
|
|
cluster[idx_clus] = entry;
|
|
idx_clus++;
|
|
if (idx_clus == nr_cluster)
|
|
goto out;
|
|
|
|
/*
|
|
* fat_collect_bhs() gets ref-count of bhs,
|
|
* so we can still use the prev_ent.
|
|
*/
|
|
prev_ent = fatent;
|
|
}
|
|
count++;
|
|
if (count == sbi->max_cluster)
|
|
break;
|
|
} while (fat_ent_next(sbi, &fatent));
|
|
}
|
|
|
|
/* Couldn't allocate the free entries */
|
|
sbi->free_clusters = 0;
|
|
sbi->free_clus_valid = 1;
|
|
sb->s_dirt = 1;
|
|
err = -ENOSPC;
|
|
|
|
out:
|
|
unlock_fat(sbi);
|
|
fatent_brelse(&fatent);
|
|
if (!err) {
|
|
if (inode_needs_sync(inode))
|
|
err = fat_sync_bhs(bhs, nr_bhs);
|
|
if (!err)
|
|
err = fat_mirror_bhs(sb, bhs, nr_bhs);
|
|
}
|
|
for (i = 0; i < nr_bhs; i++)
|
|
brelse(bhs[i]);
|
|
|
|
if (err && idx_clus)
|
|
fat_free_clusters(inode, cluster[0]);
|
|
|
|
return err;
|
|
}
|
|
|
|
int fat_free_clusters(struct inode *inode, int cluster)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
struct msdos_sb_info *sbi = MSDOS_SB(sb);
|
|
struct fatent_operations *ops = sbi->fatent_ops;
|
|
struct fat_entry fatent;
|
|
struct buffer_head *bhs[MAX_BUF_PER_PAGE];
|
|
int i, err, nr_bhs;
|
|
int first_cl = cluster;
|
|
|
|
nr_bhs = 0;
|
|
fatent_init(&fatent);
|
|
lock_fat(sbi);
|
|
do {
|
|
cluster = fat_ent_read(inode, &fatent, cluster);
|
|
if (cluster < 0) {
|
|
err = cluster;
|
|
goto error;
|
|
} else if (cluster == FAT_ENT_FREE) {
|
|
fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
|
|
__func__);
|
|
err = -EIO;
|
|
goto error;
|
|
}
|
|
|
|
/*
|
|
* Issue discard for the sectors we no longer care about,
|
|
* batching contiguous clusters into one request
|
|
*/
|
|
if (cluster != fatent.entry + 1) {
|
|
int nr_clus = fatent.entry - first_cl + 1;
|
|
|
|
sb_issue_discard(sb, fat_clus_to_blknr(sbi, first_cl),
|
|
nr_clus * sbi->sec_per_clus);
|
|
first_cl = cluster;
|
|
}
|
|
|
|
ops->ent_put(&fatent, FAT_ENT_FREE);
|
|
if (sbi->free_clusters != -1) {
|
|
sbi->free_clusters++;
|
|
sb->s_dirt = 1;
|
|
}
|
|
|
|
if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
|
|
if (sb->s_flags & MS_SYNCHRONOUS) {
|
|
err = fat_sync_bhs(bhs, nr_bhs);
|
|
if (err)
|
|
goto error;
|
|
}
|
|
err = fat_mirror_bhs(sb, bhs, nr_bhs);
|
|
if (err)
|
|
goto error;
|
|
for (i = 0; i < nr_bhs; i++)
|
|
brelse(bhs[i]);
|
|
nr_bhs = 0;
|
|
}
|
|
fat_collect_bhs(bhs, &nr_bhs, &fatent);
|
|
} while (cluster != FAT_ENT_EOF);
|
|
|
|
if (sb->s_flags & MS_SYNCHRONOUS) {
|
|
err = fat_sync_bhs(bhs, nr_bhs);
|
|
if (err)
|
|
goto error;
|
|
}
|
|
err = fat_mirror_bhs(sb, bhs, nr_bhs);
|
|
error:
|
|
fatent_brelse(&fatent);
|
|
for (i = 0; i < nr_bhs; i++)
|
|
brelse(bhs[i]);
|
|
unlock_fat(sbi);
|
|
|
|
return err;
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(fat_free_clusters);
|
|
|
|
/* 128kb is the whole sectors for FAT12 and FAT16 */
|
|
#define FAT_READA_SIZE (128 * 1024)
|
|
|
|
static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent,
|
|
unsigned long reada_blocks)
|
|
{
|
|
struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
|
|
sector_t blocknr;
|
|
int i, offset;
|
|
|
|
ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
|
|
|
|
for (i = 0; i < reada_blocks; i++)
|
|
sb_breadahead(sb, blocknr + i);
|
|
}
|
|
|
|
int fat_count_free_clusters(struct super_block *sb)
|
|
{
|
|
struct msdos_sb_info *sbi = MSDOS_SB(sb);
|
|
struct fatent_operations *ops = sbi->fatent_ops;
|
|
struct fat_entry fatent;
|
|
unsigned long reada_blocks, reada_mask, cur_block;
|
|
int err = 0, free;
|
|
|
|
lock_fat(sbi);
|
|
if (sbi->free_clusters != -1 && sbi->free_clus_valid)
|
|
goto out;
|
|
|
|
reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
|
|
reada_mask = reada_blocks - 1;
|
|
cur_block = 0;
|
|
|
|
free = 0;
|
|
fatent_init(&fatent);
|
|
fatent_set_entry(&fatent, FAT_START_ENT);
|
|
while (fatent.entry < sbi->max_cluster) {
|
|
/* readahead of fat blocks */
|
|
if ((cur_block & reada_mask) == 0) {
|
|
unsigned long rest = sbi->fat_length - cur_block;
|
|
fat_ent_reada(sb, &fatent, min(reada_blocks, rest));
|
|
}
|
|
cur_block++;
|
|
|
|
err = fat_ent_read_block(sb, &fatent);
|
|
if (err)
|
|
goto out;
|
|
|
|
do {
|
|
if (ops->ent_get(&fatent) == FAT_ENT_FREE)
|
|
free++;
|
|
} while (fat_ent_next(sbi, &fatent));
|
|
}
|
|
sbi->free_clusters = free;
|
|
sbi->free_clus_valid = 1;
|
|
sb->s_dirt = 1;
|
|
fatent_brelse(&fatent);
|
|
out:
|
|
unlock_fat(sbi);
|
|
return err;
|
|
}
|