ext4: fix online resize with mballoc

Update group infos when updating a group's descriptor.
Add group infos when adding a group's descriptor.
Refresh cache pages used by mb_alloc when changes occur.
This will probably need modifications when META_BG resizing will be allowed.

Signed-off-by: Frederic Bohe <frederic.bohe@bull.net>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>

3 files changed, 234 insertions, 56 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2c4b48519c8b..64edb09c481e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1033,6 +1033,10 @@ extern int __init init_ext4_mballoc(void);
 extern void exit_ext4_mballoc(void);
 extern void ext4_mb_free_blocks(handle_t *, struct inode *,
                 unsigned long, unsigned long, int, unsigned long *);
+extern int ext4_mb_add_more_groupinfo(struct super_block *sb,
+                ext4_group_t i, struct ext4_group_desc *desc);
+extern void ext4_mb_update_group_info(struct ext4_group_info *grp,
+                ext4_grpblk_t add);
 
 
 /* inode.c */
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 1666ac184e31..8d254ca83d9e 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2236,21 +2236,192 @@ ext4_mb_store_history(struct ext4_allocation_context *ac)
 #define ext4_mb_history_init(sb)
 #endif
 
+
+/* Create and initialize ext4_group_info data for the given group. */
+int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
+                          struct ext4_group_desc *desc)
+{
+        int i, len;
+        int metalen = 0;
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct ext4_group_info **meta_group_info;
+
+        /*
+         * First check if this group is the first of a reserved block.
+         * If it's true, we have to allocate a new table of pointers
+         * to ext4_group_info structures
+         */
+        if (group % EXT4_DESC_PER_BLOCK(sb) == 0) {
+                metalen = sizeof(*meta_group_info) <<
+                        EXT4_DESC_PER_BLOCK_BITS(sb);
+                meta_group_info = kmalloc(metalen, GFP_KERNEL);
+                if (meta_group_info == NULL) {
+                        printk(KERN_ERR "EXT4-fs: can't allocate mem for a "
+                               "buddy group\n");
+                        goto exit_meta_group_info;
+                }
+                sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)] =
+                        meta_group_info;
+        }
+
+        /*
+         * calculate needed size. if change bb_counters size,
+         * don't forget about ext4_mb_generate_buddy()
+         */
+        len = offsetof(typeof(**meta_group_info),
+                       bb_counters[sb->s_blocksize_bits + 2]);
+
+        meta_group_info =
+                sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)];
+        i = group & (EXT4_DESC_PER_BLOCK(sb) - 1);
+
+        meta_group_info[i] = kzalloc(len, GFP_KERNEL);
+        if (meta_group_info[i] == NULL) {
+                printk(KERN_ERR "EXT4-fs: can't allocate buddy mem\n");
+                goto exit_group_info;
+        }
+        set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT,
+                &(meta_group_info[i]->bb_state));
+
+        /*
+         * initialize bb_free to be able to skip
+         * empty groups without initialization
+         */
+        if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
+                meta_group_info[i]->bb_free =
+                        ext4_free_blocks_after_init(sb, group, desc);
+        } else {
+                meta_group_info[i]->bb_free =
+                        le16_to_cpu(desc->bg_free_blocks_count);
+        }
+
+        INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list);
+
+#ifdef DOUBLE_CHECK
+        {
+                struct buffer_head *bh;
+                meta_group_info[i]->bb_bitmap =
+                        kmalloc(sb->s_blocksize, GFP_KERNEL);
+                BUG_ON(meta_group_info[i]->bb_bitmap == NULL);
+                bh = ext4_read_block_bitmap(sb, group);
+                BUG_ON(bh == NULL);
+                memcpy(meta_group_info[i]->bb_bitmap, bh->b_data,
+                        sb->s_blocksize);
+                put_bh(bh);
+        }
+#endif
+
+        return 0;
+
+exit_group_info:
+        /* If a meta_group_info table has been allocated, release it now */
+        if (group % EXT4_DESC_PER_BLOCK(sb) == 0)
+                kfree(sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)]);
+exit_meta_group_info:
+        return -ENOMEM;
+} /* ext4_mb_add_groupinfo */
+
+/*
+ * Add a group to the existing groups.
+ * This function is used for online resize
+ */
+int ext4_mb_add_more_groupinfo(struct super_block *sb, ext4_group_t group,
+                               struct ext4_group_desc *desc)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct inode *inode = sbi->s_buddy_cache;
+        int blocks_per_page;
+        int block;
+        int pnum;
+        struct page *page;
+        int err;
+
+        /* Add group based on group descriptor*/
+        err = ext4_mb_add_groupinfo(sb, group, desc);
+        if (err)
+                return err;
+
+        /*
+         * Cache pages containing dynamic mb_alloc datas (buddy and bitmap
+         * datas) are set not up to date so that they will be re-initilaized
+         * during the next call to ext4_mb_load_buddy
+         */
+
+        /* Set buddy page as not up to date */
+        blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
+        block = group * 2;
+        pnum = block / blocks_per_page;
+        page = find_get_page(inode->i_mapping, pnum);
+        if (page != NULL) {
+                ClearPageUptodate(page);
+                page_cache_release(page);
+        }
+
+        /* Set bitmap page as not up to date */
+        block++;
+        pnum = block / blocks_per_page;
+        page = find_get_page(inode->i_mapping, pnum);
+        if (page != NULL) {
+                ClearPageUptodate(page);
+                page_cache_release(page);
+        }
+
+        return 0;
+}
+
+/*
+ * Update an existing group.
+ * This function is used for online resize
+ */
+void ext4_mb_update_group_info(struct ext4_group_info *grp, ext4_grpblk_t add)
+{
+        grp->bb_free += add;
+}
+
 static int ext4_mb_init_backend(struct super_block *sb)
 {
         ext4_group_t i;
-        int j, len, metalen;
+        int metalen;
         struct ext4_sb_info *sbi = EXT4_SB(sb);
-        int num_meta_group_infos =
-                (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) >>
-                        EXT4_DESC_PER_BLOCK_BITS(sb);
+        struct ext4_super_block *es = sbi->s_es;
+        int num_meta_group_infos;
+        int num_meta_group_infos_max;
+        int array_size;
         struct ext4_group_info **meta_group_info;
+        struct ext4_group_desc *desc;
+
+        /* This is the number of blocks used by GDT */
+        num_meta_group_infos = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) -
+                                1) >> EXT4_DESC_PER_BLOCK_BITS(sb);
 
+        /*
+         * This is the total number of blocks used by GDT including
+         * the number of reserved blocks for GDT.
+         * The s_group_info array is allocated with this value
+         * to allow a clean online resize without a complex
+         * manipulation of pointer.
+         * The drawback is the unused memory when no resize
+         * occurs but it's very low in terms of pages
+         * (see comments below)
+         * Need to handle this properly when META_BG resizing is allowed
+         */
+        num_meta_group_infos_max = num_meta_group_infos +
+                                le16_to_cpu(es->s_reserved_gdt_blocks);
+
+        /*
+         * array_size is the size of s_group_info array. We round it
+         * to the next power of two because this approximation is done
+         * internally by kmalloc so we can have some more memory
+         * for free here (e.g. may be used for META_BG resize).
+         */
+        array_size = 1;
+        while (array_size < sizeof(*sbi->s_group_info) *
+               num_meta_group_infos_max)
+                array_size = array_size << 1;
         /* An 8TB filesystem with 64-bit pointers requires a 4096 byte
          * kmalloc. A 128kb malloc should suffice for a 256TB filesystem.
          * So a two level scheme suffices for now. */
-        sbi->s_group_info = kmalloc(sizeof(*sbi->s_group_info) *
-                                    num_meta_group_infos, GFP_KERNEL);
+        sbi->s_group_info = kmalloc(array_size, GFP_KERNEL);
         if (sbi->s_group_info == NULL) {
                 printk(KERN_ERR "EXT4-fs: can't allocate buddy meta group\n");
                 return -ENOMEM;
@@ -2277,62 +2448,15 @@ static int ext4_mb_init_backend(struct super_block *sb)
                 sbi->s_group_info[i] = meta_group_info;
         }
 
-        /*
-         * calculate needed size. if change bb_counters size,
-         * don't forget about ext4_mb_generate_buddy()
-         */
-        len = sizeof(struct ext4_group_info);
-        len += sizeof(unsigned short) * (sb->s_blocksize_bits + 2);
         for (i = 0; i < sbi->s_groups_count; i++) {
-                struct ext4_group_desc *desc;
-
-                meta_group_info =
-                        sbi->s_group_info[i >> EXT4_DESC_PER_BLOCK_BITS(sb)];
-                j = i & (EXT4_DESC_PER_BLOCK(sb) - 1);
-
-                meta_group_info[j] = kzalloc(len, GFP_KERNEL);
-                if (meta_group_info[j] == NULL) {
-                        printk(KERN_ERR "EXT4-fs: can't allocate buddy mem\n");
-                        goto err_freebuddy;
-                }
                 desc = ext4_get_group_desc(sb, i, NULL);
                 if (desc == NULL) {
                         printk(KERN_ERR
                                 "EXT4-fs: can't read descriptor %lu\n", i);
-                        i++;
                         goto err_freebuddy;
                 }
-                set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT,
-                        &(meta_group_info[j]->bb_state));
-
-                /*
-                 * initialize bb_free to be able to skip
-                 * empty groups without initialization
-                 */
-                if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
-                        meta_group_info[j]->bb_free =
-                                ext4_free_blocks_after_init(sb, i, desc);
-                } else {
-                        meta_group_info[j]->bb_free =
-                                le16_to_cpu(desc->bg_free_blocks_count);
-                }
-
-                INIT_LIST_HEAD(&meta_group_info[j]->bb_prealloc_list);
-
-#ifdef DOUBLE_CHECK
-                {
-                        struct buffer_head *bh;
-                        meta_group_info[j]->bb_bitmap =
-                                kmalloc(sb->s_blocksize, GFP_KERNEL);
-                        BUG_ON(meta_group_info[j]->bb_bitmap == NULL);
-                        bh = ext4_read_block_bitmap(sb, i);
-                        BUG_ON(bh == NULL);
-                        memcpy(meta_group_info[j]->bb_bitmap, bh->b_data,
-                                        sb->s_blocksize);
-                        put_bh(bh);
-                }
-#endif
-
+                if (ext4_mb_add_groupinfo(sb, i, desc) != 0)
+                        goto err_freebuddy;
         }
 
         return 0;
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 9ff7b1c04239..f000fbe2cd93 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -866,6 +866,15 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
         gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
 
         /*
+         * We can allocate memory for mb_alloc based on the new group
+         * descriptor
+         */
+        if (test_opt(sb, MBALLOC)) {
+                err = ext4_mb_add_more_groupinfo(sb, input->group, gdp);
+                if (err)
+                        goto exit_journal;
+        }
+        /*
          * Make the new blocks and inodes valid next.  We do this before
          * increasing the group count so that once the group is enabled,
          * all of its blocks and inodes are already valid.
@@ -957,6 +966,8 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
         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
@@ -988,7 +999,7 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
         }
 
         /* Handle the remaining blocks in the last group only. */
-        ext4_get_group_no_and_offset(sb, o_blocks_count, NULL, &last);
+        ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
 
         if (last == 0) {
                 ext4_warning(sb, __func__,
@@ -1060,6 +1071,45 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
                    o_blocks_count + add);
         if ((err = ext4_journal_stop(handle)))
                 goto exit_put;
+
+        /*
+         * Mark mballoc pages as not up to date so that they will be updated
+         * next time they are loaded by ext4_mb_load_buddy.
+         */
+        if (test_opt(sb, MBALLOC)) {
+                struct ext4_sb_info *sbi = EXT4_SB(sb);
+                struct inode *inode = sbi->s_buddy_cache;
+                int blocks_per_page;
+                int block;
+                int pnum;
+                struct page *page;
+
+                /* Set buddy page as not up to date */
+                blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
+                block = group * 2;
+                pnum = block / blocks_per_page;
+                page = find_get_page(inode->i_mapping, pnum);
+                if (page != NULL) {
+                        ClearPageUptodate(page);
+                        page_cache_release(page);
+                }
+
+                /* Set bitmap page as not up to date */
+                block++;
+                pnum = block / blocks_per_page;
+                page = find_get_page(inode->i_mapping, pnum);
+                if (page != NULL) {
+                        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))
                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
                        ext4_blocks_count(es));