v4.19.13 snapshot.
diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
new file mode 100644
index 0000000..f58c0ca
--- /dev/null
+++ b/fs/fat/fatent.c
@@ -0,0 +1,795 @@
+/*
+ * Copyright (C) 2004, OGAWA Hirofumi
+ * Released under GPL v2.
+ */
+
+#include <linux/blkdev.h>
+#include <linux/sched/signal.h>
+#include "fat.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 DEFINE_SPINLOCK(fat12_entry_lock);
+
+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(!fat_valid_entry(sbi, 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(!fat_valid_entry(sbi, 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);
+ fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
+
+ 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:
+ fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr);
+ return -EIO;
+}
+
+static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
+ int offset, sector_t blocknr)
+{
+ const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
+
+ WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
+ fatent->fat_inode = MSDOS_SB(sb)->fat_inode;
+ fatent->bhs[0] = sb_bread(sb, blocknr);
+ if (!fatent->bhs[0]) {
+ fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)",
+ (llu)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;
+
+ spin_lock(&fat12_entry_lock);
+ if (fatent->entry & 1)
+ next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
+ else
+ next = (*ent12_p[1] << 8) | *ent12_p[0];
+ spin_unlock(&fat12_entry_lock);
+
+ 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;
+
+ spin_lock(&fat12_entry_lock);
+ 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);
+ }
+ spin_unlock(&fat12_entry_lock);
+
+ mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
+ if (fatent->nr_bhs == 2)
+ mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode);
+}
+
+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_inode(fatent->bhs[0], fatent->fat_inode);
+}
+
+static void fat32_ent_put(struct fat_entry *fatent, int new)
+{
+ WARN_ON(new & 0xf0000000);
+ new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
+ *fatent->u.ent32_p = cpu_to_le32(new);
+ mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode);
+}
+
+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 const 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 const 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 const 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)
+{
+ mutex_lock(&sbi->fat_lock);
+}
+
+static inline void unlock_fat(struct msdos_sb_info *sbi)
+{
+ mutex_unlock(&sbi->fat_lock);
+}
+
+void fat_ent_access_init(struct super_block *sb)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+
+ mutex_init(&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 void mark_fsinfo_dirty(struct super_block *sb)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+
+ if (sb_rdonly(sb) || sbi->fat_bits != 32)
+ return;
+
+ __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
+}
+
+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);
+ const 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;
+ if (sbi->fat_bits == 12) {
+ if ((offset + 1) < sb->s_blocksize) {
+ /* This entry is on bhs[0]. */
+ if (fatent->nr_bhs == 2) {
+ brelse(bhs[1]);
+ fatent->nr_bhs = 1;
+ }
+ } else {
+ /* This entry needs the next block. */
+ if (fatent->nr_bhs != 2)
+ return 0;
+ if (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);
+ const struct fatent_operations *ops = sbi->fatent_ops;
+ int err, offset;
+ sector_t blocknr;
+
+ if (!fat_valid_entry(sbi, entry)) {
+ fatent_brelse(fatent);
+ fat_fs_error(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_inode(c_bh, sbi->fat_inode);
+ if (sb->s_flags & SB_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;
+ const 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)
+{
+ const 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);
+ const 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_clus_valid &&
+ 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;
+ sbi->free_clus_valid = 1;
+ err = -ENOSPC;
+
+out:
+ unlock_fat(sbi);
+ mark_fsinfo_dirty(sb);
+ 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);
+ const 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, dirty_fsinfo = 0;
+
+ 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_error(sb, "%s: deleting FAT entry beyond EOF",
+ __func__);
+ err = -EIO;
+ goto error;
+ }
+
+ if (sbi->options.discard) {
+ /*
+ * 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,
+ GFP_NOFS, 0);
+
+ first_cl = cluster;
+ }
+ }
+
+ ops->ent_put(&fatent, FAT_ENT_FREE);
+ if (sbi->free_clusters != -1) {
+ sbi->free_clusters++;
+ dirty_fsinfo = 1;
+ }
+
+ if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
+ if (sb->s_flags & SB_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 & SB_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);
+ if (dirty_fsinfo)
+ mark_fsinfo_dirty(sb);
+
+ 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)
+{
+ const 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);
+ const 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));
+ cond_resched();
+ }
+ sbi->free_clusters = free;
+ sbi->free_clus_valid = 1;
+ mark_fsinfo_dirty(sb);
+ fatent_brelse(&fatent);
+out:
+ unlock_fat(sbi);
+ return err;
+}
+
+static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+ return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus),
+ nr_clus * sbi->sec_per_clus, GFP_NOFS, 0);
+}
+
+int fat_trim_fs(struct inode *inode, struct fstrim_range *range)
+{
+ struct super_block *sb = inode->i_sb;
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+ const struct fatent_operations *ops = sbi->fatent_ops;
+ struct fat_entry fatent;
+ u64 ent_start, ent_end, minlen, trimmed = 0;
+ u32 free = 0;
+ unsigned long reada_blocks, reada_mask, cur_block = 0;
+ int err = 0;
+
+ /*
+ * FAT data is organized as clusters, trim at the granulary of cluster.
+ *
+ * fstrim_range is in byte, convert vaules to cluster index.
+ * Treat sectors before data region as all used, not to trim them.
+ */
+ ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT);
+ ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1;
+ minlen = range->minlen >> sbi->cluster_bits;
+
+ if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size)
+ return -EINVAL;
+ if (ent_end >= sbi->max_cluster)
+ ent_end = sbi->max_cluster - 1;
+
+ reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
+ reada_mask = reada_blocks - 1;
+
+ fatent_init(&fatent);
+ lock_fat(sbi);
+ fatent_set_entry(&fatent, ent_start);
+ while (fatent.entry <= ent_end) {
+ /* 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 error;
+ do {
+ if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
+ free++;
+ } else if (free) {
+ if (free >= minlen) {
+ u32 clus = fatent.entry - free;
+
+ err = fat_trim_clusters(sb, clus, free);
+ if (err && err != -EOPNOTSUPP)
+ goto error;
+ if (!err)
+ trimmed += free;
+ err = 0;
+ }
+ free = 0;
+ }
+ } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end);
+
+ if (fatal_signal_pending(current)) {
+ err = -ERESTARTSYS;
+ goto error;
+ }
+
+ if (need_resched()) {
+ fatent_brelse(&fatent);
+ unlock_fat(sbi);
+ cond_resched();
+ lock_fat(sbi);
+ }
+ }
+ /* handle scenario when tail entries are all free */
+ if (free && free >= minlen) {
+ u32 clus = fatent.entry - free;
+
+ err = fat_trim_clusters(sb, clus, free);
+ if (err && err != -EOPNOTSUPP)
+ goto error;
+ if (!err)
+ trimmed += free;
+ err = 0;
+ }
+
+error:
+ fatent_brelse(&fatent);
+ unlock_fat(sbi);
+
+ range->len = trimmed << sbi->cluster_bits;
+
+ return err;
+}