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-rw-r--r--fs/fat/fatent.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index bac10de678cc..25d43a5e8a4d 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -4,6 +4,7 @@
*/
#include <linux/blkdev.h>
+#include <linux/sched/signal.h>
#include "fat.h"
struct fatent_operations {
@@ -690,3 +691,104 @@ 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;
+}