1 files changed, 84 insertions, 73 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3e3b45458ef..84eeb8f515a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1043,43 +1043,47 @@ static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
 	return ext4_indirect_calc_metadata_amount(inode, blocks);
 }
 
+/*
+ * Called with i_data_sem down, which is important since we can call
+ * ext4_discard_preallocations() from here.
+ */
 static void ext4_da_update_reserve_space(struct inode *inode, int used)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-	int total, mdb, mdb_free, mdb_claim = 0;
-
-	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
-	/* recalculate the number of metablocks still need to be reserved */
-	total = EXT4_I(inode)->i_reserved_data_blocks - used;
-	mdb = ext4_calc_metadata_amount(inode, total);
-
-	/* figure out how many metablocks to release */
-	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
-	mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
-
-	if (mdb_free) {
-		/* Account for allocated meta_blocks */
-		mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks;
-		BUG_ON(mdb_free < mdb_claim);
-		mdb_free -= mdb_claim;
-
-		/* update fs dirty blocks counter */
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	int mdb_free = 0;
+
+	spin_lock(&ei->i_block_reservation_lock);
+	if (unlikely(used > ei->i_reserved_data_blocks)) {
+		ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
+			 "with only %d reserved data blocks\n",
+			 __func__, inode->i_ino, used,
+			 ei->i_reserved_data_blocks);
+		WARN_ON(1);
+		used = ei->i_reserved_data_blocks;
+	}
+
+	/* Update per-inode reservations */
+	ei->i_reserved_data_blocks -= used;
+	used += ei->i_allocated_meta_blocks;
+	ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
+	ei->i_allocated_meta_blocks = 0;
+	percpu_counter_sub(&sbi->s_dirtyblocks_counter, used);
+
+	if (ei->i_reserved_data_blocks == 0) {
+		/*
+		 * We can release all of the reserved metadata blocks
+		 * only when we have written all of the delayed
+		 * allocation blocks.
+		 */
+		mdb_free = ei->i_allocated_meta_blocks;
 		percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
-		EXT4_I(inode)->i_allocated_meta_blocks = 0;
-		EXT4_I(inode)->i_reserved_meta_blocks = mdb;
+		ei->i_allocated_meta_blocks = 0;
 	}
-
-	/* update per-inode reservations */
-	BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
-	EXT4_I(inode)->i_reserved_data_blocks -= used;
-	percpu_counter_sub(&sbi->s_dirtyblocks_counter, used + mdb_claim);
 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 
-	vfs_dq_claim_block(inode, used + mdb_claim);
-
-	/*
-	 * free those over-booking quota for metadata blocks
-	 */
+	/* Update quota subsystem */
+	vfs_dq_claim_block(inode, used);
 	if (mdb_free)
 		vfs_dq_release_reservation_block(inode, mdb_free);
 
@@ -1088,7 +1092,8 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
 	 * there aren't any writers on the inode, we can discard the
 	 * inode's preallocations.
 	 */
-	if (!total && (atomic_read(&inode->i_writecount) == 0))
+	if ((ei->i_reserved_data_blocks == 0) &&
+	    (atomic_read(&inode->i_writecount) == 0))
 		ext4_discard_preallocations(inode);
 }
 
@@ -1801,7 +1806,8 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
 {
 	int retries = 0;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-	unsigned long md_needed, mdblocks, total = 0;
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	unsigned long md_needed, md_reserved, total = 0;
 
 	/*
 	 * recalculate the amount of metadata blocks to reserve
@@ -1809,35 +1815,44 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
 	 * worse case is one extent per block
 	 */
 repeat:
-	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
-	total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
-	mdblocks = ext4_calc_metadata_amount(inode, total);
-	BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks);
-
-	md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
+	spin_lock(&ei->i_block_reservation_lock);
+	md_reserved = ei->i_reserved_meta_blocks;
+	md_needed = ext4_calc_metadata_amount(inode, nrblocks);
 	total = md_needed + nrblocks;
-	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+	spin_unlock(&ei->i_block_reservation_lock);
 
 	/*
 	 * Make quota reservation here to prevent quota overflow
 	 * later. Real quota accounting is done at pages writeout
 	 * time.
 	 */
-	if (vfs_dq_reserve_block(inode, total))
+	if (vfs_dq_reserve_block(inode, total)) {
+		/* 
+		 * We tend to badly over-estimate the amount of
+		 * metadata blocks which are needed, so if we have
+		 * reserved any metadata blocks, try to force out the
+		 * inode and see if we have any better luck.
+		 */
+		if (md_reserved && retries++ <= 3)
+			goto retry;
 		return -EDQUOT;
+	}
 
 	if (ext4_claim_free_blocks(sbi, total)) {
 		vfs_dq_release_reservation_block(inode, total);
 		if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
+		retry:
+			if (md_reserved)
+				write_inode_now(inode, (retries == 3));
 			yield();
 			goto repeat;
 		}
 		return -ENOSPC;
 	}
-	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
-	EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
-	EXT4_I(inode)->i_reserved_meta_blocks += md_needed;
-	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+	spin_lock(&ei->i_block_reservation_lock);
+	ei->i_reserved_data_blocks += nrblocks;
+	ei->i_reserved_meta_blocks += md_needed;
+	spin_unlock(&ei->i_block_reservation_lock);
 
 	return 0;       /* success */
 }
@@ -1845,49 +1860,45 @@ repeat:
 static void ext4_da_release_space(struct inode *inode, int to_free)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-	int total, mdb, mdb_free, release;
+	struct ext4_inode_info *ei = EXT4_I(inode);
 
 	if (!to_free)
 		return;		/* Nothing to release, exit */
 
 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 
-	if (!EXT4_I(inode)->i_reserved_data_blocks) {
+	if (unlikely(to_free > ei->i_reserved_data_blocks)) {
 		/*
-		 * if there is no reserved blocks, but we try to free some
-		 * then the counter is messed up somewhere.
-		 * but since this function is called from invalidate
-		 * page, it's harmless to return without any action
+		 * if there aren't enough reserved blocks, then the
+		 * counter is messed up somewhere.  Since this
+		 * function is called from invalidate page, it's
+		 * harmless to return without any action.
 		 */
-		printk(KERN_INFO "ext4 delalloc try to release %d reserved "
-			    "blocks for inode %lu, but there is no reserved "
-			    "data blocks\n", to_free, inode->i_ino);
-		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
-		return;
+		ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
+			 "ino %lu, to_free %d with only %d reserved "
+			 "data blocks\n", inode->i_ino, to_free,
+			 ei->i_reserved_data_blocks);
+		WARN_ON(1);
+		to_free = ei->i_reserved_data_blocks;
 	}
+	ei->i_reserved_data_blocks -= to_free;
 
-	/* recalculate the number of metablocks still need to be reserved */
-	total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
-	mdb = ext4_calc_metadata_amount(inode, total);
-
-	/* figure out how many metablocks to release */
-	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
-	mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
-
-	release = to_free + mdb_free;
-
-	/* update fs dirty blocks counter for truncate case */
-	percpu_counter_sub(&sbi->s_dirtyblocks_counter, release);
+	if (ei->i_reserved_data_blocks == 0) {
+		/*
+		 * We can release all of the reserved metadata blocks
+		 * only when we have written all of the delayed
+		 * allocation blocks.
+		 */
+		to_free += ei->i_allocated_meta_blocks;
+		ei->i_allocated_meta_blocks = 0;
+	}
 
-	/* update per-inode reservations */
-	BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
-	EXT4_I(inode)->i_reserved_data_blocks -= to_free;
+	/* update fs dirty blocks counter */
+	percpu_counter_sub(&sbi->s_dirtyblocks_counter, to_free);
 
-	BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
-	EXT4_I(inode)->i_reserved_meta_blocks = mdb;
 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 
-	vfs_dq_release_reservation_block(inode, release);
+	vfs_dq_release_reservation_block(inode, to_free);
 }
 
 static void ext4_da_page_release_reservation(struct page *page,