[PATCH v12 06/13] exfat: add fat entry operations

Namjae Jeon
2020-01-20T12:45:07Z

This adds the implementation of fat entry operations for exfat.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
---
fs/exfat/fatent.c | 463 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 463 insertions(+)
create mode 100644 fs/exfat/fatent.c

diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c
new file mode 100644
index 000000000000..a855b1769a96
--- /dev/null
+++ b/fs/exfat/fatent.c
@@ -0,0 +1,463 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/slab.h>
+#include <asm/unaligned.h>
+#include <linux/buffer_head.h>
+
+#include "exfat_raw.h"
+#include "exfat_fs.h"
+
+static int exfat_mirror_bh(struct super_block *sb, sector_t sec,
+ struct buffer_head *bh)
+{
+ struct buffer_head *c_bh;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ sector_t sec2;
+ int err = 0;
+
+ if (sbi->FAT2_start_sector != sbi->FAT1_start_sector) {
+ sec2 = sec - sbi->FAT1_start_sector + sbi->FAT2_start_sector;
+ c_bh = sb_getblk(sb, sec2);
+ if (!c_bh)
+ return -ENOMEM;
+ memcpy(c_bh->b_data, bh->b_data, sb->s_blocksize);
+ set_buffer_uptodate(c_bh);
+ mark_buffer_dirty(c_bh);
+ if (sb->s_flags & SB_SYNCHRONOUS)
+ err = sync_dirty_buffer(c_bh);
+ brelse(c_bh);
+ }
+
+ return err;
+}
+
+static int __exfat_ent_get(struct super_block *sb, unsigned int loc,
+ unsigned int *content)
+{
+ unsigned int off;
+ sector_t sec;
+ struct buffer_head *bh;
+
+ sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
+ off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
+
+ bh = sb_bread(sb, sec);
+ if (!bh)
+ return -EIO;
+
+ *content = le32_to_cpu(*(__le32 *)(&bh->b_data[off]));
+
+ /* remap reserved clusters to simplify code */
+ if (*content > EXFAT_BAD_CLUSTER)
+ *content = EXFAT_EOF_CLUSTER;
+
+ brelse(bh);
+ return 0;
+}
+
+int exfat_ent_set(struct super_block *sb, unsigned int loc,
+ unsigned int content)
+{
+ unsigned int off;
+ sector_t sec;
+ __le32 *fat_entry;
+ struct buffer_head *bh;
+
+ sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
+ off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
+
+ bh = sb_bread(sb, sec);
+ if (!bh)
+ return -EIO;
+
+ fat_entry = (__le32 *)&(bh->b_data[off]);
+ *fat_entry = cpu_to_le32(content);
+ exfat_update_bh(sb, bh, sb->s_flags & SB_SYNCHRONOUS);
+ exfat_mirror_bh(sb, sec, bh);
+ brelse(bh);
+ return 0;
+}
+
+static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
+ unsigned int clus)
+{
+ if (clus < EXFAT_FIRST_CLUSTER || sbi->num_clusters <= clus)
+ return false;
+ return true;
+}
+
+int exfat_ent_get(struct super_block *sb, unsigned int loc,
+ unsigned int *content)
+{
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ int err;
+
+ if (!is_valid_cluster(sbi, loc)) {
+ exfat_fs_error(sb, "invalid access to FAT (entry 0x%08x)",
+ loc);
+ return -EIO;
+ }
+
+ err = __exfat_ent_get(sb, loc, content);
+ if (err) {
+ exfat_fs_error(sb,
+ "failed to access to FAT (entry 0x%08x, err:%d)",
+ loc, err);
+ return err;
+ }
+
+ if (*content == EXFAT_FREE_CLUSTER) {
+ exfat_fs_error(sb,
+ "invalid access to FAT free cluster (entry 0x%08x)",
+ loc);
+ return -EIO;
+ }
+
+ if (*content == EXFAT_BAD_CLUSTER) {
+ exfat_fs_error(sb,
+ "invalid access to FAT bad cluster (entry 0x%08x)",
+ loc);
+ return -EIO;
+ }
+
+ if (*content != EXFAT_EOF_CLUSTER && !is_valid_cluster(sbi, *content)) {
+ exfat_fs_error(sb,
+ "invalid access to FAT (entry 0x%08x) bogus content (0x%08x)",
+ loc, *content);
+ return -EIO;
+ }
+
+ return 0;
+}
+
+int exfat_chain_cont_cluster(struct super_block *sb, unsigned int chain,
+ unsigned int len)
+{
+ if (!len)
+ return 0;
+
+ while (len > 1) {
+ if (exfat_ent_set(sb, chain, chain + 1))
+ return -EIO;
+ chain++;
+ len--;
+ }
+
+ if (exfat_ent_set(sb, chain, EXFAT_EOF_CLUSTER))
+ return -EIO;
+ return 0;
+}
+
+int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
+{
+ unsigned int num_clusters = 0;
+ unsigned int clu;
+ struct super_block *sb = inode->i_sb;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+ /* invalid cluster number */
+ if (p_chain->dir == EXFAT_FREE_CLUSTER ||
+ p_chain->dir == EXFAT_EOF_CLUSTER ||
+ p_chain->dir < EXFAT_FIRST_CLUSTER)
+ return 0;
+
+ /* no cluster to truncate */
+ if (p_chain->size == 0)
+ return 0;
+
+ /* check cluster validation */
+ if (p_chain->dir < 2 && p_chain->dir >= sbi->num_clusters) {
+ exfat_msg(sb, KERN_ERR, "invalid start cluster (%u)",
+ p_chain->dir);
+ return -EIO;
+ }
+
+ set_bit(EXFAT_SB_DIRTY, &sbi->s_state);
+ clu = p_chain->dir;
+
+ if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+ do {
+ exfat_clear_bitmap(inode, clu);
+ clu++;
+
+ num_clusters++;
+ } while (num_clusters < p_chain->size);
+ } else {
+ do {
+ exfat_clear_bitmap(inode, clu);
+
+ if (exfat_get_next_cluster(sb, &clu))
+ goto dec_used_clus;
+
+ num_clusters++;
+ } while (clu != EXFAT_EOF_CLUSTER);
+ }
+
+dec_used_clus:
+ sbi->used_clusters -= num_clusters;
+ return 0;
+}
+
+int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
+ unsigned int *ret_clu)
+{
+ unsigned int clu, next;
+ unsigned int count = 0;
+
+ next = p_chain->dir;
+ if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+ *ret_clu = next + p_chain->size - 1;
+ return 0;
+ }
+
+ do {
+ count++;
+ clu = next;
+ if (exfat_ent_get(sb, clu, &next))
+ return -EIO;
+ } while (next != EXFAT_EOF_CLUSTER);
+
+ if (p_chain->size != count) {
+ exfat_fs_error(sb,
+ "bogus directory size (clus : ondisk(%d) != counted(%d))",
+ p_chain->size, count);
+ return -EIO;
+ }
+
+ *ret_clu = clu;
+ return 0;
+}
+
+static inline int exfat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
+{
+ int i, err = 0;
+
+ for (i = 0; i < nr_bhs; i++)
+ write_dirty_buffer(bhs[i], 0);
+
+ for (i = 0; i < nr_bhs; i++) {
+ wait_on_buffer(bhs[i]);
+ if (!err && !buffer_uptodate(bhs[i]))
+ err = -EIO;
+ }
+ return err;
+}
+
+int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
+{
+ struct super_block *sb = dir->i_sb;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ struct buffer_head *bhs[MAX_BUF_PER_PAGE];
+ int nr_bhs = MAX_BUF_PER_PAGE;
+ sector_t blknr, last_blknr;
+ int err, i, n;
+
+ blknr = exfat_cluster_to_sector(sbi, clu);
+ last_blknr = blknr + sbi->sect_per_clus;
+
+ if (last_blknr > sbi->num_sectors && sbi->num_sectors > 0) {
+ exfat_fs_error_ratelimit(sb,
+ "%s: out of range(sect:%llu len:%u)",
+ __func__, (unsigned long long)blknr,
+ sbi->sect_per_clus);
+ return -EIO;
+ }
+
+ /* Zeroing the unused blocks on this cluster */
+ n = 0;
+ while (blknr < last_blknr) {
+ bhs[n] = sb_getblk(sb, blknr);
+ if (!bhs[n]) {
+ err = -ENOMEM;
+ goto release_bhs;
+ }
+ memset(bhs[n]->b_data, 0, sb->s_blocksize);
+ exfat_update_bh(sb, bhs[n], 0);
+
+ n++;
+ blknr++;
+
+ if (n == nr_bhs) {
+ if (IS_DIRSYNC(dir)) {
+ err = exfat_sync_bhs(bhs, n);
+ if (err)
+ goto release_bhs;
+ }
+
+ for (i = 0; i < n; i++)
+ brelse(bhs[i]);
+ n = 0;
+ }
+ }
+
+ if (IS_DIRSYNC(dir)) {
+ err = exfat_sync_bhs(bhs, n);
+ if (err)
+ goto release_bhs;
+ }
+
+ for (i = 0; i < n; i++)
+ brelse(bhs[i]);
+
+ return 0;
+
+release_bhs:
+ exfat_msg(sb, KERN_ERR, "failed zeroed sect %llu\n",
+ (unsigned long long)blknr);
+ for (i = 0; i < n; i++)
+ bforget(bhs[i]);
+ return err;
+}
+
+int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
+ struct exfat_chain *p_chain)
+{
+ int ret = -ENOSPC;
+ unsigned int num_clusters = 0, total_cnt;
+ unsigned int hint_clu, new_clu, last_clu = EXFAT_EOF_CLUSTER;
+ struct super_block *sb = inode->i_sb;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+ total_cnt = EXFAT_DATA_CLUSTER_COUNT(sbi);
+
+ if (unlikely(total_cnt < sbi->used_clusters)) {
+ exfat_fs_error_ratelimit(sb,
+ "%s: invalid used clusters(t:%u,u:%u)\n",
+ __func__, total_cnt, sbi->used_clusters);
+ return -EIO;
+ }
+
+ if (num_alloc > total_cnt - sbi->used_clusters)
+ return -ENOSPC;
+
+ hint_clu = p_chain->dir;
+ /* find new cluster */
+ if (hint_clu == EXFAT_EOF_CLUSTER) {
+ if (sbi->clu_srch_ptr < EXFAT_FIRST_CLUSTER) {
+ exfat_msg(sb, KERN_ERR,
+ "sbi->clu_srch_ptr is invalid (%u)\n",
+ sbi->clu_srch_ptr);
+ sbi->clu_srch_ptr = EXFAT_FIRST_CLUSTER;
+ }
+
+ hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
+ if (hint_clu == EXFAT_EOF_CLUSTER)
+ return -ENOSPC;
+ }
+
+ /* check cluster validation */
+ if (hint_clu < EXFAT_FIRST_CLUSTER && hint_clu >= sbi->num_clusters) {
+ exfat_msg(sb, KERN_ERR, "hint_cluster is invalid (%u)\n",
+ hint_clu);
+ hint_clu = EXFAT_FIRST_CLUSTER;
+ if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+ if (exfat_chain_cont_cluster(sb, p_chain->dir,
+ num_clusters))
+ return -EIO;
+ p_chain->flags = ALLOC_FAT_CHAIN;
+ }
+ }
+
+ set_bit(EXFAT_SB_DIRTY, &sbi->s_state);
+
+ p_chain->dir = EXFAT_EOF_CLUSTER;
+
+ while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
+ EXFAT_EOF_CLUSTER) {
+ if (new_clu != hint_clu &&
+ p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+ if (exfat_chain_cont_cluster(sb, p_chain->dir,
+ num_clusters)) {
+ ret = -EIO;
+ goto free_cluster;
+ }
+ p_chain->flags = ALLOC_FAT_CHAIN;
+ }
+
+ /* update allocation bitmap */
+ if (exfat_set_bitmap(inode, new_clu)) {
+ ret = -EIO;
+ goto free_cluster;
+ }
+
+ num_clusters++;
+
+ /* update FAT table */
+ if (p_chain->flags == ALLOC_FAT_CHAIN) {
+ if (exfat_ent_set(sb, new_clu, EXFAT_EOF_CLUSTER)) {
+ ret = -EIO;
+ goto free_cluster;
+ }
+ }
+
+ if (p_chain->dir == EXFAT_EOF_CLUSTER) {
+ p_chain->dir = new_clu;
+ } else if (p_chain->flags == ALLOC_FAT_CHAIN) {
+ if (exfat_ent_set(sb, last_clu, new_clu)) {
+ ret = -EIO;
+ goto free_cluster;
+ }
+ }
+ last_clu = new_clu;
+
+ if (--num_alloc == 0) {
+ sbi->clu_srch_ptr = hint_clu;
+ sbi->used_clusters += num_clusters;
+
+ p_chain->size += num_clusters;
+ return 0;
+ }
+
+ hint_clu = new_clu + 1;
+ if (hint_clu >= sbi->num_clusters) {
+ hint_clu = EXFAT_FIRST_CLUSTER;
+
+ if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+ if (exfat_chain_cont_cluster(sb, p_chain->dir,
+ num_clusters)) {
+ ret = -EIO;
+ goto free_cluster;
+ }
+ p_chain->flags = ALLOC_FAT_CHAIN;
+ }
+ }
+ }
+free_cluster:
+ if (num_clusters)
+ exfat_free_cluster(inode, p_chain);
+ return ret;
+}
+
+int exfat_count_num_clusters(struct super_block *sb,
+ struct exfat_chain *p_chain, unsigned int *ret_count)
+{
+ unsigned int i, count;
+ unsigned int clu;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+ if (!p_chain->dir || p_chain->dir == EXFAT_EOF_CLUSTER) {
+ *ret_count = 0;
+ return 0;
+ }
+
+ if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+ *ret_count = p_chain->size;
+ return 0;
+ }
+
+ clu = p_chain->dir;
+ count = 0;
+ for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters; i++) {
+ count++;
+ if (exfat_ent_get(sb, clu, &clu))
+ return -EIO;
+ if (clu == EXFAT_EOF_CLUSTER)
+ break;
+ }
+
+ *ret_count = count;
+ return 0;
+}
--
2.17.1