1 files changed, 120 insertions, 0 deletions

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 45853e0d1f21..e428f23215c0 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -107,6 +107,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
         desc = ext4_get_group_desc(sb, block_group, NULL);
         if (!desc)
                 return NULL;
+
         bitmap_blk = ext4_inode_bitmap(sb, desc);
         bh = sb_getblk(sb, bitmap_blk);
         if (unlikely(!bh)) {
@@ -123,6 +124,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 unlock_buffer(bh);
                 return bh;
         }
+
         ext4_lock_group(sb, block_group);
         if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
                 ext4_init_inode_bitmap(sb, bh, block_group, desc);
@@ -133,6 +135,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 return bh;
         }
         ext4_unlock_group(sb, block_group);
+
         if (buffer_uptodate(bh)) {
                 /*
                  * if not uninit if bh is uptodate,
@@ -712,8 +715,17 @@ static int ext4_claim_inode(struct super_block *sb,
 {
         int free = 0, retval = 0, count;
         struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct ext4_group_info *grp = ext4_get_group_info(sb, group);
         struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group, NULL);
 
+        /*
+         * We have to be sure that new inode allocation does not race with
+         * inode table initialization, because otherwise we may end up
+         * allocating and writing new inode right before sb_issue_zeroout
+         * takes place and overwriting our new inode with zeroes. So we
+         * take alloc_sem to prevent it.
+         */
+        down_read(&grp->alloc_sem);
         ext4_lock_group(sb, group);
         if (ext4_set_bit(ino, inode_bitmap_bh->b_data)) {
                 /* not a free inode */
@@ -724,6 +736,7 @@ static int ext4_claim_inode(struct super_block *sb,
         if ((group == 0 && ino < EXT4_FIRST_INO(sb)) ||
                         ino > EXT4_INODES_PER_GROUP(sb)) {
                 ext4_unlock_group(sb, group);
+                up_read(&grp->alloc_sem);
                 ext4_error(sb, "reserved inode or inode > inodes count - "
                            "block_group = %u, inode=%lu", group,
                            ino + group * EXT4_INODES_PER_GROUP(sb));
@@ -772,6 +785,7 @@ static int ext4_claim_inode(struct super_block *sb,
         gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
 err_ret:
         ext4_unlock_group(sb, group);
+        up_read(&grp->alloc_sem);
         return retval;
 }
 
@@ -1205,3 +1219,109 @@ unsigned long ext4_count_dirs(struct super_block * sb)
         }
         return count;
 }
+
+/*
+ * Zeroes not yet zeroed inode table - just write zeroes through the whole
+ * inode table. Must be called without any spinlock held. The only place
+ * where it is called from on active part of filesystem is ext4lazyinit
+ * thread, so we do not need any special locks, however we have to prevent
+ * inode allocation from the current group, so we take alloc_sem lock, to
+ * block ext4_claim_inode until we are finished.
+ */
+extern int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
+                                 int barrier)
+{
+        struct ext4_group_info *grp = ext4_get_group_info(sb, group);
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct ext4_group_desc *gdp = NULL;
+        struct buffer_head *group_desc_bh;
+        handle_t *handle;
+        ext4_fsblk_t blk;
+        int num, ret = 0, used_blks = 0;
+        unsigned long flags = BLKDEV_IFL_WAIT;
+
+        /* This should not happen, but just to be sure check this */
+        if (sb->s_flags & MS_RDONLY) {
+                ret = 1;
+                goto out;
+        }
+
+        gdp = ext4_get_group_desc(sb, group, &group_desc_bh);
+        if (!gdp)
+                goto out;
+
+        /*
+         * We do not need to lock this, because we are the only one
+         * handling this flag.
+         */
+        if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED))
+                goto out;
+
+        handle = ext4_journal_start_sb(sb, 1);
+        if (IS_ERR(handle)) {
+                ret = PTR_ERR(handle);
+                goto out;
+        }
+
+        down_write(&grp->alloc_sem);
+        /*
+         * If inode bitmap was already initialized there may be some
+         * used inodes so we need to skip blocks with used inodes in
+         * inode table.
+         */
+        if (!(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)))
+                used_blks = DIV_ROUND_UP((EXT4_INODES_PER_GROUP(sb) -
+                            ext4_itable_unused_count(sb, gdp)),
+                            sbi->s_inodes_per_block);
+
+        blk = ext4_inode_table(sb, gdp) + used_blks;
+        num = sbi->s_itb_per_group - used_blks;
+
+        BUFFER_TRACE(group_desc_bh, "get_write_access");
+        ret = ext4_journal_get_write_access(handle,
+                                            group_desc_bh);
+        if (ret)
+                goto err_out;
+
+        if (unlikely(num > EXT4_INODES_PER_GROUP(sb))) {
+                ext4_error(sb, "Something is wrong with group %u\n"
+                           "Used itable blocks: %d"
+                           "Itable blocks per group: %lu\n",
+                           group, used_blks, sbi->s_itb_per_group);
+                ret = 1;
+                goto err_out;
+        }
+
+        /*
+         * Skip zeroout if the inode table is full. But we set the ZEROED
+         * flag anyway, because obviously, when it is full it does not need
+         * further zeroing.
+         */
+        if (unlikely(num == 0))
+                goto skip_zeroout;
+
+        ext4_debug("going to zero out inode table in group %d\n",
+                   group);
+        if (barrier)
+                flags |= BLKDEV_IFL_BARRIER;
+        ret = sb_issue_zeroout(sb, blk, num, GFP_NOFS, flags);
+        if (ret < 0)
+                goto err_out;
+
+skip_zeroout:
+        ext4_lock_group(sb, group);
+        gdp->bg_flags |= cpu_to_le16(EXT4_BG_INODE_ZEROED);
+        gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
+        ext4_unlock_group(sb, group);
+
+        BUFFER_TRACE(group_desc_bh,
+                     "call ext4_handle_dirty_metadata");
+        ret = ext4_handle_dirty_metadata(handle, NULL,
+                                         group_desc_bh);
+
+err_out:
+        up_write(&grp->alloc_sem);
+        ext4_journal_stop(handle);
+out:
+        return ret;
+}