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new helper: end_writeback()

PATCH In review Al Viro 4 participants 4 messages Jun 8, 2010 – Jun 9, 2010

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Al Viro

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#0 lore raw

PATCH 7/58 new helper: end_writeback()

Essentially, the minimal variant of ->evict_inode(). It's a trimmed-down clear_inode(), sans any fs callbacks. Once it returns we know that no async writeback will be happening; every ->evict_inode() instance should do that once and do that before doing anything ->write_inode() could interfere with (e.g. freeing the on-disk inode).

Signed-off-by Al Viro <[email protected]>
---
 fs/hugetlbfs/inode.c |    2 +-
 fs/inode.c           |   12 ++++++++++++
 include/linux/fs.h   |    1 +
 3 files changed, 14 insertions(+), 1 deletions(-)
fs/hugetlbfs/inode.c +1 -1
index bf1a2f4..6e5bd42 100644
@@ -374,7 +374,7 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
 static void hugetlbfs_evict_inode(struct inode *inode)
 {
 	truncate_hugepages(inode, 0);
-	clear_inode(inode);
+	end_writeback(inode);
 }
 
 static inline void
fs/inode.c +12 -0
index 139d475..3f45360 100644
@@ -294,6 +294,18 @@ void __iget(struct inode *inode)
 	inodes_stat.nr_unused--;
 }
 
+void end_writeback(struct inode *inode)
+{
+	might_sleep();
+	BUG_ON(inode->i_data.nrpages);
+	BUG_ON(!list_empty(&inode->i_data.private_list));
+	BUG_ON(!(inode->i_state & I_FREEING));
+	BUG_ON(inode->i_state & I_CLEAR);
+	inode_sync_wait(inode);
+	inode->i_state = I_FREEING | I_CLEAR;
+}
+EXPORT_SYMBOL(end_writeback);
+
 /**
  * clear_inode - clear an inode
  * @inode: inode to clear
include/linux/fs.h +1 -0
index 788b003..cea7283 100644
@@ -2170,6 +2170,7 @@ extern void unlock_new_inode(struct inode *);
 extern void __iget(struct inode * inode);
 extern void iget_failed(struct inode *);
 extern void clear_inode(struct inode *);
+extern void end_writeback(struct inode *);
 extern void destroy_inode(struct inode *);
 extern void __destroy_inode(struct inode *);
 extern struct inode *new_inode(struct super_block *);
Signature · 1 line
1.5.6.5
#1 lore raw
Quoted 7 lines · Al Viro

Essentially, the minimal variant of ->evict_inode(). It's a trimmed-down clear_inode(), sans any fs callbacks. Once it returns we know that no async writeback will be happening; every ->evict_inode() instance should do that once and do that before doing anything ->write_inode() could interfere with (e.g. freeing the on-disk inode).

Naming seems a bit unfortunate - this really sounds like something in page writeback. In fact I'd almost bet we had a function with that name there in the past.

Care to slap an inode_ prefix on it?

maintainer
#2 lore raw
Quoted 9 lines · Christoph Hellwig
Quoted 7 lines · Al Viro

Essentially, the minimal variant of ->evict_inode(). It's a trimmed-down clear_inode(), sans any fs callbacks. Once it returns we know that no async writeback will be happening; every ->evict_inode() instance should do that once and do that before doing anything ->write_inode() could interfere with (e.g. freeing the on-disk inode).

Quoted 5 lines

Naming seems a bit unfortunate - this really sounds like something in page writeback. In fact I'd almost bet we had a function with that name there in the past.

Care to slap an inode_ prefix on it?

Ehh... I'd been tempted to call it end_async or something like that. I'm not particulary fond of the name; any better suggestions are welcome.

The point of what's being done in that function is that it acts as a barrier; "wait for async activity to run down; new one won't be started since it's already marked I_FREEING".

#3 lore raw
Quoted 14 lines · Al Viro
Quoted 13 lines · Christoph Hellwig
Quoted 7 lines · Al Viro

Essentially, the minimal variant of ->evict_inode(). It's a trimmed-down clear_inode(), sans any fs callbacks. Once it returns we know that no async writeback will be happening; every ->evict_inode() instance should do that once and do that before doing anything ->write_inode() could interfere with (e.g. freeing the on-disk inode).

Naming seems a bit unfortunate - this really sounds like something in page writeback. In fact I'd almost bet we had a function with that name there in the past.

Quoted 8 lines
Quoted 1 line

Care to slap an inode_ prefix on it?

Ehh... I'd been tempted to call it end_async or something like that. I'm not particulary fond of the name; any better suggestions are welcome.

The point of what's being done in that function is that it acts as a barrier; "wait for async activity to run down; new one won't be started since it's already marked I_FREEING".

It was odd for me to. I had to go look at code to understand what it's for. I would prefer the word "wait" in the name or barrier. eg. wait_writeback. end_writeback sounds like something you should call from ->write_end

Just my $0.017
Boaz