ext4: Add blocks added during resize to bitmap

With this change new blocks added during resize
are marked as free in the block bitmap and the
group is flagged with EXT4_GROUP_INFO_NEED_INIT_BIT
flag.  This makes sure when mballoc tries to allocate
blocks from the new group we would reload the
buddy information using the bitmap present in the disk.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

3 files changed, 34 insertions, 118 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index a0c23b03a264..c54192e2384e 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -20,6 +20,7 @@
 #include "ext4.h"
 #include "ext4_jbd2.h"
 #include "group.h"
+#include "mballoc.h"
 
 /*
  * balloc.c contains the blocks allocation and deallocation routines
@@ -350,62 +351,43 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 }
 
 /**
- * ext4_free_blocks_sb() -- Free given blocks and update quota
+ * ext4_add_groupblocks() -- Add given blocks to an existing group
  * @handle:                     handle to this transaction
  * @sb:                         super block
- * @block:                      start physcial block to free
+ * @block:                      start physcial block to add to the block group
  * @count:                      number of blocks to free
- * @pdquot_freed_blocks:        pointer to quota
  *
- * XXX This function is only used by the on-line resizing code, which
- * should probably be fixed up to call the mballoc variant.  There
- * this needs to be cleaned up later; in fact, I'm not convinced this
- * is 100% correct in the face of the mballoc code.  The online resizing
- * code needs to be fixed up to more tightly (and correctly) interlock
- * with the mballoc code.
+ * This marks the blocks as free in the bitmap. We ask the
+ * mballoc to reload the buddy after this by setting group
+ * EXT4_GROUP_INFO_NEED_INIT_BIT flag
  */
-void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
-                         ext4_fsblk_t block, unsigned long count,
-                         unsigned long *pdquot_freed_blocks)
+void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
+                         ext4_fsblk_t block, unsigned long count)
 {
         struct buffer_head *bitmap_bh = NULL;
         struct buffer_head *gd_bh;
         ext4_group_t block_group;
         ext4_grpblk_t bit;
         unsigned int i;
-        unsigned int overflow;
         struct ext4_group_desc *desc;
         struct ext4_super_block *es;
         struct ext4_sb_info *sbi;
         int err = 0, ret;
-        ext4_grpblk_t group_freed;
+        ext4_grpblk_t blocks_freed;
+        struct ext4_group_info *grp;
 
-        *pdquot_freed_blocks = 0;
         sbi = EXT4_SB(sb);
         es = sbi->s_es;
-        if (block < le32_to_cpu(es->s_first_data_block) ||
-            block + count < block ||
-            block + count > ext4_blocks_count(es)) {
-                ext4_error(sb, "ext4_free_blocks",
-                           "Freeing blocks not in datazone - "
-                           "block = %llu, count = %lu", block, count);
-                goto error_return;
-        }
-
-        ext4_debug("freeing block(s) %llu-%llu\n", block, block + count - 1);
+        ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
 
-do_more:
-        overflow = 0;
         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
         /*
          * Check to see if we are freeing blocks across a group
          * boundary.
          */
         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
-                overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
-                count -= overflow;
+                goto error_return;
         }
-        brelse(bitmap_bh);
         bitmap_bh = ext4_read_block_bitmap(sb, block_group);
         if (!bitmap_bh)
                 goto error_return;
@@ -418,18 +400,17 @@ do_more:
             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
             in_range(block + count - 1, ext4_inode_table(sb, desc),
                      sbi->s_itb_per_group)) {
-                ext4_error(sb, "ext4_free_blocks",
-                           "Freeing blocks in system zones - "
+                ext4_error(sb, __func__,
+                           "Adding blocks in system zones - "
                            "Block = %llu, count = %lu",
                            block, count);
                 goto error_return;
         }
 
         /*
-         * We are about to start releasing blocks in the bitmap,
+         * We are about to add blocks to the bitmap,
          * so we need undo access.
          */
-        /* @@@ check errors */
         BUFFER_TRACE(bitmap_bh, "getting undo access");
         err = ext4_journal_get_undo_access(handle, bitmap_bh);
         if (err)
@@ -445,87 +426,28 @@ do_more:
         if (err)
                 goto error_return;
 
-        jbd_lock_bh_state(bitmap_bh);
-
-        for (i = 0, group_freed = 0; i < count; i++) {
-                /*
-                 * An HJ special.  This is expensive...
-                 */
-#ifdef CONFIG_JBD2_DEBUG
-                jbd_unlock_bh_state(bitmap_bh);
-                {
-                        struct buffer_head *debug_bh;
-                        debug_bh = sb_find_get_block(sb, block + i);
-                        if (debug_bh) {
-                                BUFFER_TRACE(debug_bh, "Deleted!");
-                                if (!bh2jh(bitmap_bh)->b_committed_data)
-                                        BUFFER_TRACE(debug_bh,
-                                                "No commited data in bitmap");
-                                BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
-                                __brelse(debug_bh);
-                        }
-                }
-                jbd_lock_bh_state(bitmap_bh);
-#endif
-                if (need_resched()) {
-                        jbd_unlock_bh_state(bitmap_bh);
-                        cond_resched();
-                        jbd_lock_bh_state(bitmap_bh);
-                }
-                /* @@@ This prevents newly-allocated data from being
-                 * freed and then reallocated within the same
-                 * transaction.
-                 *
-                 * Ideally we would want to allow that to happen, but to
-                 * do so requires making jbd2_journal_forget() capable of
-                 * revoking the queued write of a data block, which
-                 * implies blocking on the journal lock.  *forget()
-                 * cannot block due to truncate races.
-                 *
-                 * Eventually we can fix this by making jbd2_journal_forget()
-                 * return a status indicating whether or not it was able
-                 * to revoke the buffer.  On successful revoke, it is
-                 * safe not to set the allocation bit in the committed
-                 * bitmap, because we know that there is no outstanding
-                 * activity on the buffer any more and so it is safe to
-                 * reallocate it.
-                 */
-                BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
-                J_ASSERT_BH(bitmap_bh,
-                                bh2jh(bitmap_bh)->b_committed_data != NULL);
-                ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
-                                bh2jh(bitmap_bh)->b_committed_data);
-
-                /*
-                 * We clear the bit in the bitmap after setting the committed
-                 * data bit, because this is the reverse order to that which
-                 * the allocator uses.
-                 */
+        for (i = 0, blocks_freed = 0; i < count; i++) {
                 BUFFER_TRACE(bitmap_bh, "clear bit");
                 if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
                                                 bit + i, bitmap_bh->b_data)) {
-                        jbd_unlock_bh_state(bitmap_bh);
                         ext4_error(sb, __func__,
                                    "bit already cleared for block %llu",
                                    (ext4_fsblk_t)(block + i));
-                        jbd_lock_bh_state(bitmap_bh);
                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
                 } else {
-                        group_freed++;
+                        blocks_freed++;
                 }
         }
-        jbd_unlock_bh_state(bitmap_bh);
-
         spin_lock(sb_bgl_lock(sbi, block_group));
-        le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
+        le16_add_cpu(&desc->bg_free_blocks_count, blocks_freed);
         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
         spin_unlock(sb_bgl_lock(sbi, block_group));
-        percpu_counter_add(&sbi->s_freeblocks_counter, count);
+        percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
 
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
                 spin_lock(sb_bgl_lock(sbi, flex_group));
-                sbi->s_flex_groups[flex_group].free_blocks += count;
+                sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
                 spin_unlock(sb_bgl_lock(sbi, flex_group));
         }
 
@@ -536,15 +458,17 @@ do_more:
         /* And the group descriptor block */
         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
         ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
-        if (!err) err = ret;
-        *pdquot_freed_blocks += group_freed;
-
-        if (overflow && !err) {
-                block += count;
-                count = overflow;
-                goto do_more;
-        }
+        if (!err)
+                err = ret;
         sb->s_dirt = 1;
+        /*
+         * request to reload the buddy with the
+         * new bitmap information
+         */
+        grp = ext4_get_group_info(sb, block_group);
+        set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
+        ext4_mb_update_group_info(grp, blocks_freed);
+
 error_return:
         brelse(bitmap_bh);
         ext4_std_error(sb, err);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 5125c1f6e7ec..8021bf558d1e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1014,9 +1014,8 @@ extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
 extern int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
 extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
                         ext4_fsblk_t block, unsigned long count, int metadata);
-extern void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
-                                ext4_fsblk_t block, unsigned long count,
-                                unsigned long *pdquot_freed_blocks);
+extern void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
+                                ext4_fsblk_t block, unsigned long count);
 extern ext4_fsblk_t ext4_count_free_blocks(struct super_block *);
 extern void ext4_check_blocks_bitmap(struct super_block *);
 extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 1865d6a53de3..526db73701b4 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -977,9 +977,7 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
         struct buffer_head *bh;
         handle_t *handle;
         int err;
-        unsigned long freed_blocks;
         ext4_group_t group;
-        struct ext4_group_info *grp;
 
         /* We don't need to worry about locking wrt other resizers just
          * yet: we're going to revalidate es->s_blocks_count after
@@ -1077,7 +1075,8 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
         unlock_super(sb);
         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
                    o_blocks_count + add);
-        ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
+        /* We add the blocks to the bitmap and set the group need init bit */
+        ext4_add_groupblocks(handle, sb, o_blocks_count, add);
         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
                    o_blocks_count + add);
         if ((err = ext4_journal_stop(handle)))
@@ -1120,12 +1119,6 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
                         ClearPageUptodate(page);
                         page_cache_release(page);
                 }
-
-                /* Get the info on the last group */
-                grp = ext4_get_group_info(sb, group);
-
-                /* Update free blocks in group info */
-                ext4_mb_update_group_info(grp, add);
         }
 
         if (test_opt(sb, DEBUG))