2 files changed, 267 insertions, 0 deletions

diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index b3db22649426..045995c8ce5a 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -20,6 +20,7 @@
 #include <linux/ext3_jbd.h>
 #include <linux/quotaops.h>
 #include <linux/buffer_head.h>
+#include <linux/blkdev.h>
 
 /*
  * balloc.c contains the blocks allocation and deallocation routines
@@ -39,6 +40,21 @@
 
 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 
+/*
+ * Calculate the block group number and offset, given a block number
+ */
+static void ext3_get_group_no_and_offset(struct super_block *sb,
+        ext3_fsblk_t blocknr, unsigned long *blockgrpp, ext3_grpblk_t *offsetp)
+{
+        struct ext3_super_block *es = EXT3_SB(sb)->s_es;
+
+        blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
+        if (offsetp)
+                *offsetp = blocknr % EXT3_BLOCKS_PER_GROUP(sb);
+        if (blockgrpp)
+                *blockgrpp = blocknr / EXT3_BLOCKS_PER_GROUP(sb);
+}
+
 /**
  * ext3_get_group_desc() -- load group descriptor from disk
  * @sb:                 super block
@@ -1885,3 +1901,253 @@ unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
         return ext3_bg_num_gdb_meta(sb,group);
 
 }
+
+/**
+ * ext3_trim_all_free -- function to trim all free space in alloc. group
+ * @sb:                 super block for file system
+ * @group:              allocation group to trim
+ * @start:              first group block to examine
+ * @max:                last group block to examine
+ * @gdp:                allocation group description structure
+ * @minblocks:          minimum extent block count
+ *
+ * ext3_trim_all_free walks through group's block bitmap searching for free
+ * blocks. When the free block is found, it tries to allocate this block and
+ * consequent free block to get the biggest free extent possible, until it
+ * reaches any used block. Then issue a TRIM command on this extent and free
+ * the extent in the block bitmap. This is done until whole group is scanned.
+ */
+ext3_grpblk_t ext3_trim_all_free(struct super_block *sb, unsigned int group,
+                                ext3_grpblk_t start, ext3_grpblk_t max,
+                                ext3_grpblk_t minblocks)
+{
+        handle_t *handle;
+        ext3_grpblk_t next, free_blocks, bit, freed, count = 0;
+        ext3_fsblk_t discard_block;
+        struct ext3_sb_info *sbi;
+        struct buffer_head *gdp_bh, *bitmap_bh = NULL;
+        struct ext3_group_desc *gdp;
+        int err = 0, ret = 0;
+
+        /*
+         * We will update one block bitmap, and one group descriptor
+         */
+        handle = ext3_journal_start_sb(sb, 2);
+        if (IS_ERR(handle))
+                return PTR_ERR(handle);
+
+        bitmap_bh = read_block_bitmap(sb, group);
+        if (!bitmap_bh) {
+                err = -EIO;
+                goto err_out;
+        }
+
+        BUFFER_TRACE(bitmap_bh, "getting undo access");
+        err = ext3_journal_get_undo_access(handle, bitmap_bh);
+        if (err)
+                goto err_out;
+
+        gdp = ext3_get_group_desc(sb, group, &gdp_bh);
+        if (!gdp) {
+                err = -EIO;
+                goto err_out;
+        }
+
+        BUFFER_TRACE(gdp_bh, "get_write_access");
+        err = ext3_journal_get_write_access(handle, gdp_bh);
+        if (err)
+                goto err_out;
+
+        free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
+        sbi = EXT3_SB(sb);
+
+         /* Walk through the whole group */
+        while (start < max) {
+                start = bitmap_search_next_usable_block(start, bitmap_bh, max);
+                if (start < 0)
+                        break;
+                next = start;
+
+                /*
+                 * Allocate contiguous free extents by setting bits in the
+                 * block bitmap
+                 */
+                while (next < max
+                        && claim_block(sb_bgl_lock(sbi, group),
+                                        next, bitmap_bh)) {
+                        next++;
+                }
+
+                 /* We did not claim any blocks */
+                if (next == start)
+                        continue;
+
+                discard_block = (ext3_fsblk_t)start +
+                                ext3_group_first_block_no(sb, group);
+
+                /* Update counters */
+                spin_lock(sb_bgl_lock(sbi, group));
+                le16_add_cpu(&gdp->bg_free_blocks_count, start - next);
+                spin_unlock(sb_bgl_lock(sbi, group));
+                percpu_counter_sub(&sbi->s_freeblocks_counter, next - start);
+
+                /* Do not issue a TRIM on extents smaller than minblocks */
+                if ((next - start) < minblocks)
+                        goto free_extent;
+
+                 /* Send the TRIM command down to the device */
+                err = sb_issue_discard(sb, discard_block, next - start,
+                                       GFP_NOFS, 0);
+                count += (next - start);
+free_extent:
+                freed = 0;
+
+                /*
+                 * Clear bits in the bitmap
+                 */
+                for (bit = start; bit < next; bit++) {
+                        BUFFER_TRACE(bitmap_bh, "clear bit");
+                        if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, group),
+                                                bit, bitmap_bh->b_data)) {
+                                ext3_error(sb, __func__,
+                                        "bit already cleared for block "E3FSBLK,
+                                         (unsigned long)bit);
+                                BUFFER_TRACE(bitmap_bh, "bit already cleared");
+                        } else {
+                                freed++;
+                        }
+                }
+
+                /* Update couters */
+                spin_lock(sb_bgl_lock(sbi, group));
+                le16_add_cpu(&gdp->bg_free_blocks_count, freed);
+                spin_unlock(sb_bgl_lock(sbi, group));
+                percpu_counter_add(&sbi->s_freeblocks_counter, freed);
+
+                start = next;
+                if (err < 0) {
+                        if (err != -EOPNOTSUPP)
+                                ext3_warning(sb, __func__, "Discard command "
+                                             "returned error %d\n", err);
+                        break;
+                }
+
+                if (fatal_signal_pending(current)) {
+                        err = -ERESTARTSYS;
+                        break;
+                }
+
+                cond_resched();
+
+                /* No more suitable extents */
+                if ((free_blocks - count) < minblocks)
+                        break;
+        }
+
+        /* We dirtied the bitmap block */
+        BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
+        ret = ext3_journal_dirty_metadata(handle, bitmap_bh);
+        if (!err)
+                err = ret;
+
+        /* And the group descriptor block */
+        BUFFER_TRACE(gdp_bh, "dirtied group descriptor block");
+        ret = ext3_journal_dirty_metadata(handle, gdp_bh);
+        if (!err)
+                err = ret;
+
+        ext3_debug("trimmed %d blocks in the group %d\n",
+                count, group);
+
+err_out:
+        if (err)
+                count = err;
+        ext3_journal_stop(handle);
+        brelse(bitmap_bh);
+
+        return count;
+}
+
+/**
+ * ext3_trim_fs() -- trim ioctl handle function
+ * @sb:                 superblock for filesystem
+ * @start:              First Byte to trim
+ * @len:                number of Bytes to trim from start
+ * @minlen:             minimum extent length in Bytes
+ *
+ * ext3_trim_fs goes through all allocation groups containing Bytes from
+ * start to start+len. For each such a group ext3_trim_all_free function
+ * is invoked to trim all free space.
+ */
+int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
+{
+        ext3_grpblk_t last_block, first_block, free_blocks;
+        unsigned long first_group, last_group;
+        unsigned long group, ngroups;
+        struct ext3_group_desc *gdp;
+        struct ext3_super_block *es = EXT3_SB(sb)->s_es;
+        uint64_t start, len, minlen, trimmed;
+        ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count);
+        int ret = 0;
+
+        start = range->start >> sb->s_blocksize_bits;
+        len = range->len >> sb->s_blocksize_bits;
+        minlen = range->minlen >> sb->s_blocksize_bits;
+        trimmed = 0;
+
+        if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb)))
+                return -EINVAL;
+        if (start >= max_blks)
+                goto out;
+        if (start < le32_to_cpu(es->s_first_data_block)) {
+                len -= le32_to_cpu(es->s_first_data_block) - start;
+                start = le32_to_cpu(es->s_first_data_block);
+        }
+        if (start + len > max_blks)
+                len = max_blks - start;
+
+        ngroups = EXT3_SB(sb)->s_groups_count;
+        smp_rmb();
+
+        /* Determine first and last group to examine based on start and len */
+        ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start,
+                                     &first_group, &first_block);
+        ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) (start + len),
+                                     &last_group, &last_block);
+        last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group;
+        last_block = EXT3_BLOCKS_PER_GROUP(sb);
+
+        if (first_group > last_group)
+                return -EINVAL;
+
+        for (group = first_group; group <= last_group; group++) {
+                gdp = ext3_get_group_desc(sb, group, NULL);
+                if (!gdp)
+                        break;
+
+                free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
+                if (free_blocks < minlen)
+                        continue;
+
+                if (len >= EXT3_BLOCKS_PER_GROUP(sb))
+                        len -= (EXT3_BLOCKS_PER_GROUP(sb) - first_block);
+                else
+                        last_block = first_block + len;
+
+                ret = ext3_trim_all_free(sb, group, first_block,
+                                        last_block, minlen);
+                if (ret < 0)
+                        break;
+
+                trimmed += ret;
+                first_block = 0;
+        }
+
+        if (ret >= 0)
+                ret = 0;
+
+out:
+        range->len = trimmed * sb->s_blocksize;
+
+        return ret;
+}
diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
index 6ce1bca01724..a443965946bb 100644
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -856,6 +856,7 @@ extern struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
 extern int ext3_should_retry_alloc(struct super_block *sb, int *retries);
 extern void ext3_init_block_alloc_info(struct inode *);
 extern void ext3_rsv_window_add(struct super_block *sb, struct ext3_reserve_window_node *rsv);
+extern int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range);
 
 /* dir.c */
 extern int ext3_check_dir_entry(const char *, struct inode *,