/* * Copyright (C) 2004, OGAWA Hirofumi * Released under GPL v2. */ #include <linux/module.h> #include <linux/fs.h> #include <linux/msdos_fs.h> struct fatent_operations { void (*ent_blocknr)(struct super_block *, int, int *, sector_t *); void (*ent_set_ptr)(struct fat_entry *, int); int (*ent_bread)(struct super_block *, struct fat_entry *, int, sector_t); int (*ent_get)(struct fat_entry *); void (*ent_put)(struct fat_entry *, int); int (*ent_next)(struct fat_entry *); }; static void fat12_ent_blocknr(struct super_block *sb, int entry, int *offset, sector_t *blocknr) { struct msdos_sb_info *sbi = MSDOS_SB(sb); int bytes = entry + (entry >> 1); WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); *offset = bytes & (sb->s_blocksize - 1); *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); } static void fat_ent_blocknr(struct super_block *sb, int entry, int *offset, sector_t *blocknr) { struct msdos_sb_info *sbi = MSDOS_SB(sb); int bytes = (entry << sbi->fatent_shift); WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); *offset = bytes & (sb->s_blocksize - 1); *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); } static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) { struct buffer_head **bhs = fatent->bhs; if (fatent->nr_bhs == 1) { WARN_ON(offset >= (bhs[0]->b_size - 1)); fatent->u.ent12_p[0] = bhs[0]->b_data + offset; fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); } else { WARN_ON(offset != (bhs[0]->b_size - 1)); fatent->u.ent12_p[0] = bhs[0]->b_data + offset; fatent->u.ent12_p[1] = bhs[1]->b_data; } } static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) { WARN_ON(offset & (2 - 1)); fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); } static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) { WARN_ON(offset & (4 - 1)); fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); } static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, int offset, sector_t blocknr) { struct buffer_head **bhs = fatent->bhs; WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); bhs[0] = sb_bread(sb, blocknr); if (!bhs[0]) goto err; if ((offset + 1) < sb->s_blocksize) fatent->nr_bhs = 1; else { /* This entry is block boundary, it needs the next block */ blocknr++; bhs[1] = sb_bread(sb, blocknr); if (!bhs[1]) goto err_brelse; fatent->nr_bhs = 2; } fat12_ent_set_ptr(fatent, offset); return 0; err_brelse: brelse(bhs[0]); err: printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", (unsigned long long)blocknr); return -EIO; } static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, int offset, sector_t blocknr) { struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); fatent->bhs[0] = sb_bread(sb, blocknr); if (!fatent->bhs[0]) { printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", (unsigned long long)blocknr); return -EIO; } fatent->nr_bhs = 1; ops->ent_set_ptr(fatent, offset); return 0; } static int fat12_ent_get(struct fat_entry *fatent) { u8 **ent12_p = fatent->u.ent12_p; int next; if (fatent->entry & 1) next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); else next = (*ent12_p[1] << 8) | *ent12_p[0]; next &= 0x0fff; if (next >= BAD_FAT12) next = FAT_ENT_EOF; return next; } static int fat16_ent_get(struct fat_entry *fatent) { int next = le16_to_cpu(*fatent->u.ent16_p); WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); if (next >= BAD_FAT16) next = FAT_ENT_EOF; return next; } static int fat32_ent_get(struct fat_entry *fatent) { int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); if (next >= BAD_FAT32) next = FAT_ENT_EOF; return next; } static void fat12_ent_put(struct fat_entry *fatent, int new) { u8 **ent12_p = fatent->u.ent12_p; if (new == FAT_ENT_EOF) new = EOF_FAT12; if (fatent->entry & 1) { *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); *ent12_p[1] = new >> 4; } else { *ent12_p[0] = new & 0xff; *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); } mark_buffer_dirty(fatent->bhs[0]); if (fatent->nr_bhs == 2) mark_buffer_dirty(fatent->bhs[1]); } static void fat16_ent_put(struct fat_entry *fatent, int new) { if (new == FAT_ENT_EOF) new = EOF_FAT16; *fatent->u.ent16_p = cpu_to_le16(new); mark_buffer_dirty(fatent->bhs[0]); } static void fat32_ent_put(struct fat_entry *fatent, int new) { if (new == FAT_ENT_EOF) new = EOF_FAT32; WARN_ON(new & 0xf0000000); new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; *fatent->u.ent32_p = cpu_to_le32(new); mark_buffer_dirty(fatent->bhs[0]); } static int fat12_ent_next(struct fat_entry *fatent) { u8 **ent12_p = fatent->u.ent12_p; struct buffer_head **bhs = fatent->bhs; u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); fatent->entry++; if (fatent->nr_bhs == 1) { WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2))); WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { ent12_p[0] = nextp - 1; ent12_p[1] = nextp; return 1; } } else { WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); ent12_p[0] = nextp - 1; ent12_p[1] = nextp; brelse(bhs[0]); bhs[0] = bhs[1]; fatent->nr_bhs = 1; return 1; } ent12_p[0] = NULL; ent12_p[1] = NULL; return 0; } static int fat16_ent_next(struct fat_entry *fatent) { const struct buffer_head *bh = fatent->bhs[0]; fatent->entry++; if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { fatent->u.ent16_p++; return 1; } fatent->u.ent16_p = NULL; return 0; } static int fat32_ent_next(struct fat_entry *fatent) { const struct buffer_head *bh = fatent->bhs[0]; fatent->entry++; if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { fatent->u.ent32_p++; return 1; } fatent->u.ent32_p = NULL; return 0; } static struct fatent_operations fat12_ops = { .ent_blocknr = fat12_ent_blocknr, .ent_set_ptr = fat12_ent_set_ptr, .ent_bread = fat12_ent_bread, .ent_get = fat12_ent_get, .ent_put = fat12_ent_put, .ent_next = fat12_ent_next, }; static struct fatent_operations fat16_ops = { .ent_blocknr = fat_ent_blocknr, .ent_set_ptr = fat16_ent_set_ptr, .ent_bread = fat_ent_bread, .ent_get = fat16_ent_get, .ent_put = fat16_ent_put, .ent_next = fat16_ent_next, }; static struct fatent_operations fat32_ops = { .ent_blocknr = fat_ent_blocknr, .ent_set_ptr = fat32_ent_set_ptr, .ent_bread = fat_ent_bread, .ent_get = fat32_ent_get, .ent_put = fat32_ent_put, .ent_next = fat32_ent_next, }; static inline void lock_fat(struct msdos_sb_info *sbi) { down(&sbi->fat_lock); } static inline void unlock_fat(struct msdos_sb_info *sbi) { up(&sbi->fat_lock); } void fat_ent_access_init(struct super_block *sb) { struct msdos_sb_info *sbi = MSDOS_SB(sb); init_MUTEX(&sbi->fat_lock); switch (sbi->fat_bits) { case 32: sbi->fatent_shift = 2; sbi->fatent_ops = &fat32_ops; break; case 16: sbi->fatent_shift = 1; sbi->fatent_ops = &fat16_ops; break; case 12: sbi->fatent_shift = -1; sbi->fatent_ops = &fat12_ops; break; } } static inline int fat_ent_update_ptr(struct super_block *sb, struct fat_entry *fatent, int offset, sector_t blocknr) { struct msdos_sb_info *sbi = MSDOS_SB(sb); struct fatent_operations *ops = sbi->fatent_ops; struct buffer_head **bhs = fatent->bhs; /* Is this fatent's blocks including this entry? */ if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) return 0; /* Does this entry need the next block? */ if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) { if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1)) return 0; } ops->ent_set_ptr(fatent, offset); return 1; } int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) { struct super_block *sb = inode->i_sb; struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); struct fatent_operations *ops = sbi->fatent_ops; int err, offset; sector_t blocknr; if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { fatent_brelse(fatent); fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry); return -EIO; } fatent_set_entry(fatent, entry); ops->ent_blocknr(sb, entry, &offset, &blocknr); if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { fatent_brelse(fatent); err = ops->ent_bread(sb, fatent, offset, blocknr); if (err) return err; } return ops->ent_get(fatent); } /* FIXME: We can write the blocks as more big chunk. */ static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, int nr_bhs) { struct msdos_sb_info *sbi = MSDOS_SB(sb); struct buffer_head *c_bh; int err, n, copy; err = 0; for (copy = 1; copy < sbi->fats; copy++) { sector_t backup_fat = sbi->fat_length * copy; for (n = 0; n < nr_bhs; n++) { c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); if (!c_bh) { err = -ENOMEM; goto error; } memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); set_buffer_uptodate(c_bh); mark_buffer_dirty(c_bh); if (sb->s_flags & MS_SYNCHRONOUS) err = sync_dirty_buffer(c_bh); brelse(c_bh); if (err) goto error; } } error: return err; } int fat_ent_write(struct inode *inode, struct fat_entry *fatent, int new, int wait) { struct super_block *sb = inode->i_sb; struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; int err; ops->ent_put(fatent, new); if (wait) { err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); if (err) return err; } return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); } static inline int fat_ent_next(struct msdos_sb_info *sbi, struct fat_entry *fatent) { if (sbi->fatent_ops->ent_next(fatent)) { if (fatent->entry < sbi->max_cluster) return 1; } return 0; } static inline int fat_ent_read_block(struct super_block *sb, struct fat_entry *fatent) { struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; sector_t blocknr; int offset; fatent_brelse(fatent); ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); return ops->ent_bread(sb, fatent, offset, blocknr); } static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, struct fat_entry *fatent) { int n, i; for (n = 0; n < fatent->nr_bhs; n++) { for (i = 0; i < *nr_bhs; i++) { if (fatent->bhs[n] == bhs[i]) break; } if (i == *nr_bhs) { get_bh(fatent->bhs[n]); bhs[i] = fatent->bhs[n]; (*nr_bhs)++; } } } int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_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, prev_ent; struct buffer_head *bhs[MAX_BUF_PER_PAGE]; int i, count, err, nr_bhs, idx_clus; BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ lock_fat(sbi); if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) { unlock_fat(sbi); return -ENOSPC; } err = nr_bhs = idx_clus = 0; count = FAT_START_ENT; fatent_init(&prev_ent); fatent_init(&fatent); fatent_set_entry(&fatent, sbi->prev_free + 1); while (count < sbi->max_cluster) { if (fatent.entry >= sbi->max_cluster) fatent.entry = FAT_START_ENT; fatent_set_entry(&fatent, fatent.entry); err = fat_ent_read_block(sb, &fatent); if (err) goto out; /* Find the free entries in a block */ do { if (ops->ent_get(&fatent) == FAT_ENT_FREE) { int entry = fatent.entry; /* 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--; 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; 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]); fat_clusters_flush(sb); 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; 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", __FUNCTION__); err = -EIO; goto error; } ops->ent_put(&fatent, FAT_ENT_FREE); if (sbi->free_clusters != -1) sbi->free_clusters++; 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); fat_clusters_flush(sb); return err; } EXPORT_SYMBOL(fat_free_clusters); 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; int err = 0, free; lock_fat(sbi); if (sbi->free_clusters != -1) goto out; free = 0; fatent_init(&fatent); fatent_set_entry(&fatent, FAT_START_ENT); while (fatent.entry < sbi->max_cluster) { 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; fatent_brelse(&fatent); out: unlock_fat(sbi); return err; }