From 654762df2ec7d61b05acc788afbffaba52d658fe Mon Sep 17 00:00:00 2001
From: Hyeongseok Kim <hyeongseok@gmail.com>
Date: Thu, 4 Mar 2021 09:20:35 +0900
Subject: [Backport 654762df2ec7] exfat: add support ioctl and FITRIM function

Add FITRIM ioctl to enable discarding unused blocks while mounted.
As current exFAT doesn't have generic ioctl handler, add empty ioctl
function first, and add FITRIM handler.

Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
---
 src/balloc.c   | 80 +++++++++++++++++++++++++++++++++++++++++++++
 src/dir.c      |  5 +++
 src/exfat_fs.h |  4 +++
 src/file.c     | 53 ++++++++++++++++++++++++++++++
 4 files changed, 142 insertions(+)

diff --git a/src/balloc.c b/src/balloc.c
index 411fb0a8da10d40be5610f55f72280d44eb03ee7..78bc87d5a11bf9688dbef42ad9c3b4f0c232c0f1 100644
--- a/src/balloc.c
+++ b/src/balloc.c
@@ -264,3 +264,83 @@ int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
 	*ret_count = count;
 	return 0;
 }
+
+int exfat_trim_fs(struct inode *inode, struct fstrim_range *range)
+{
+	unsigned int trim_begin, trim_end, count, next_free_clu;
+	u64 clu_start, clu_end, trim_minlen, trimmed_total = 0;
+	struct super_block *sb = inode->i_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	int err = 0;
+
+	clu_start = max_t(u64, range->start >> sbi->cluster_size_bits,
+				EXFAT_FIRST_CLUSTER);
+	clu_end = clu_start + (range->len >> sbi->cluster_size_bits) - 1;
+	trim_minlen = range->minlen >> sbi->cluster_size_bits;
+
+	if (clu_start >= sbi->num_clusters || range->len < sbi->cluster_size)
+		return -EINVAL;
+
+	if (clu_end >= sbi->num_clusters)
+		clu_end = sbi->num_clusters - 1;
+
+	mutex_lock(&sbi->bitmap_lock);
+
+	trim_begin = trim_end = exfat_find_free_bitmap(sb, clu_start);
+	if (trim_begin == EXFAT_EOF_CLUSTER)
+		goto unlock;
+
+	next_free_clu = exfat_find_free_bitmap(sb, trim_end + 1);
+	if (next_free_clu == EXFAT_EOF_CLUSTER)
+		goto unlock;
+
+	do {
+		if (next_free_clu == trim_end + 1) {
+			/* extend trim range for continuous free cluster */
+			trim_end++;
+		} else {
+			/* trim current range if it's larger than trim_minlen */
+			count = trim_end - trim_begin + 1;
+			if (count >= trim_minlen) {
+				err = sb_issue_discard(sb,
+					exfat_cluster_to_sector(sbi, trim_begin),
+					count * sbi->sect_per_clus, GFP_NOFS, 0);
+				if (err)
+					goto unlock;
+
+				trimmed_total += count;
+			}
+
+			/* set next start point of the free hole */
+			trim_begin = trim_end = next_free_clu;
+		}
+
+		if (next_free_clu >= clu_end)
+			break;
+
+		if (fatal_signal_pending(current)) {
+			err = -ERESTARTSYS;
+			goto unlock;
+		}
+
+		next_free_clu = exfat_find_free_bitmap(sb, next_free_clu + 1);
+	} while (next_free_clu != EXFAT_EOF_CLUSTER &&
+			next_free_clu > trim_end);
+
+	/* try to trim remainder */
+	count = trim_end - trim_begin + 1;
+	if (count >= trim_minlen) {
+		err = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, trim_begin),
+			count * sbi->sect_per_clus, GFP_NOFS, 0);
+		if (err)
+			goto unlock;
+
+		trimmed_total += count;
+	}
+
+unlock:
+	mutex_unlock(&sbi->bitmap_lock);
+	range->len = trimmed_total << sbi->cluster_size_bits;
+
+	return err;
+}
diff --git a/src/dir.c b/src/dir.c
index 916797077aad4ab45cd73c36a5012fd2653fef33..e1d5536de948b3dcd4667cf3074b51462ddb0697 100644
--- a/src/dir.c
+++ b/src/dir.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/compat.h>
 #include <linux/bio.h>
 #include <linux/buffer_head.h>
 
@@ -306,6 +307,10 @@ const struct file_operations exfat_dir_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
 	.iterate	= exfat_iterate,
+	.unlocked_ioctl = exfat_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = exfat_compat_ioctl,
+#endif
 	.fsync		= exfat_file_fsync,
 };
 
diff --git a/src/exfat_fs.h b/src/exfat_fs.h
index e05e0a3152c0e5c415bd042e40d680194f02b49e..169d0b602f5e7c06c8889b38d83abcfad2e8382c 100644
--- a/src/exfat_fs.h
+++ b/src/exfat_fs.h
@@ -412,6 +412,7 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu);
 void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync);
 unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu);
 int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count);
+int exfat_trim_fs(struct inode *inode, struct fstrim_range *range);
 
 /* file.c */
 extern const struct file_operations exfat_file_operations;
@@ -421,6 +422,9 @@
 int exfat_getattr(const struct path *path, struct kstat *stat,
 		unsigned int request_mask, unsigned int query_flags);
 int exfat_file_fsync(struct file *file, loff_t start, loff_t end, int datasync);
+long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
+long exfat_compat_ioctl(struct file *filp, unsigned int cmd,
+				unsigned long arg);
 
 /* namei.c */
 extern const struct dentry_operations exfat_dentry_ops;
diff --git a/src/file.c b/src/file.c
index f783cf38dd8e885aa1cf33c91ffeaa3b87a120eb..6af0191b648f1601890f32e3df0f5db81cce8ea4 100644
--- a/src/file.c
+++ b/src/file.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/compat.h>
 #include <linux/cred.h>
 #include <linux/buffer_head.h>
 #include <linux/blkdev.h>
@@ -350,6 +351,54 @@ int exfat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	return error;
 }
 
+static int exfat_ioctl_fitrim(struct inode *inode, unsigned long arg)
+{
+	struct request_queue *q = bdev_get_queue(inode->i_sb->s_bdev);
+	struct fstrim_range range;
+	int ret = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!blk_queue_discard(q))
+		return -EOPNOTSUPP;
+
+	if (copy_from_user(&range, (struct fstrim_range __user *)arg, sizeof(range)))
+		return -EFAULT;
+
+	range.minlen = max_t(unsigned int, range.minlen,
+				q->limits.discard_granularity);
+
+	ret = exfat_trim_fs(inode, &range);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user((struct fstrim_range __user *)arg, &range, sizeof(range)))
+		return -EFAULT;
+
+	return 0;
+}
+
+long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+
+	switch (cmd) {
+	case FITRIM:
+		return exfat_ioctl_fitrim(inode, arg);
+	default:
+		return -ENOTTY;
+	}
+}
+
+#ifdef CONFIG_COMPAT
+long exfat_compat_ioctl(struct file *filp, unsigned int cmd,
+				unsigned long arg)
+{
+	return exfat_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
 int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 {
 	struct inode *inode = filp->f_mapping->host;
@@ -370,6 +419,10 @@ const struct file_operations exfat_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read_iter	= generic_file_read_iter,
 	.write_iter	= generic_file_write_iter,
+	.unlocked_ioctl = exfat_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = exfat_compat_ioctl,
+#endif
 	.mmap		= generic_file_mmap,
 	.fsync		= exfat_file_fsync,
 	.splice_read	= generic_file_splice_read,
-- 
2.31.1