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SubjectRe: [PATCH] vfs: Split generic_forget_inode() so that hugetlbfs does not have to copy it
On Wed 03-06-09 11:56:38, Christoph Hellwig wrote:
> On Tue, Jun 02, 2009 at 06:20:34PM +0200, Jan Kara wrote:
> > Hugetlbfs needs to do special things instead of truncate_inode_pages().
> > Currently, it copied generic_forget_inode() except for truncate_inode_pages()
> > call which is asking for trouble (the code there isn't trivial). So create a
> > separate function generic_detach_inode() which does all the list magic done in
> > generic_forget_inode() and call it from hugetlbfs_forget_inode().
>
> Looks good to me, but long term I'd just prefer to have
> truncate_inode_pages do the right thing for huge pages..
That would be nice but I don't know how to do that (being completely
ignorant of hugepages ;).

> > +/*
> > + * Remove inode from inode lists, write it if it's dirty.
> > + *
> > + * Returns 1 if inode should be completely destroyed.
> > + */
>
> Please make this a kerneldoc comment. And mention that this is just
> and internal helper that can go away any time.
Fixed. Resulting patch below...

--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
---
From 2dcb48492bd7f56e56a52e7b8ea867c1942a7c34 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 2 Jun 2009 18:06:24 +0200
Subject: [PATCH] vfs: Split generic_forget_inode() so that hugetlbfs does not have to copy it (V2)

Hugetlbfs needs to do special things instead of truncate_inode_pages().
Currently, it copied generic_forget_inode() except for truncate_inode_pages()
call which is asking for trouble (the code there isn't trivial). So create a
separate function generic_detach_inode() which does all the list magic done in
generic_forget_inode() and call it from hugetlbfs_forget_inode().

Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/hugetlbfs/inode.c | 33 ++++-----------------------------
fs/inode.c | 21 +++++++++++++++++++--
include/linux/fs.h | 1 +
3 files changed, 24 insertions(+), 31 deletions(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index c1462d4..ef65d9e 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -380,36 +380,11 @@ static void hugetlbfs_delete_inode(struct inode *inode)

static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
{
- struct super_block *sb = inode->i_sb;
-
- if (!hlist_unhashed(&inode->i_hash)) {
- if (!(inode->i_state & (I_DIRTY|I_SYNC)))
- list_move(&inode->i_list, &inode_unused);
- inodes_stat.nr_unused++;
- if (!sb || (sb->s_flags & MS_ACTIVE)) {
- spin_unlock(&inode_lock);
- return;
- }
- inode->i_state |= I_WILL_FREE;
- spin_unlock(&inode_lock);
- /*
- * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
- * in our backing_dev_info.
- */
- write_inode_now(inode, 1);
- spin_lock(&inode_lock);
- inode->i_state &= ~I_WILL_FREE;
- inodes_stat.nr_unused--;
- hlist_del_init(&inode->i_hash);
+ if (generic_detach_inode(inode)) {
+ truncate_hugepages(inode, 0);
+ clear_inode(inode);
+ destroy_inode(inode);
}
- list_del_init(&inode->i_list);
- list_del_init(&inode->i_sb_list);
- inode->i_state |= I_FREEING;
- inodes_stat.nr_inodes--;
- spin_unlock(&inode_lock);
- truncate_hugepages(inode, 0);
- clear_inode(inode);
- destroy_inode(inode);
}

static void hugetlbfs_drop_inode(struct inode *inode)
diff --git a/fs/inode.c b/fs/inode.c
index 0571983..990bf83 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1183,7 +1183,16 @@ void generic_delete_inode(struct inode *inode)
}
EXPORT_SYMBOL(generic_delete_inode);

-static void generic_forget_inode(struct inode *inode)
+/**
+ * generic_detach_inode - remove inode from inode lists
+ * @inode: inode to remove
+ *
+ * Remove inode from inode lists, write it if it's dirty. This is just an
+ * internal VFS helper exported for hugetlbfs. Do not use!
+ *
+ * Returns 1 if inode should be completely destroyed.
+ */
+int generic_detach_inode(struct inode *inode)
{
struct super_block *sb = inode->i_sb;

@@ -1193,7 +1202,7 @@ static void generic_forget_inode(struct inode *inode)
inodes_stat.nr_unused++;
if (sb->s_flags & MS_ACTIVE) {
spin_unlock(&inode_lock);
- return;
+ return 0;
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_WILL_FREE;
@@ -1211,6 +1220,14 @@ static void generic_forget_inode(struct inode *inode)
inode->i_state |= I_FREEING;
inodes_stat.nr_inodes--;
spin_unlock(&inode_lock);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(generic_detach_inode);
+
+static void generic_forget_inode(struct inode *inode)
+{
+ if (!generic_detach_inode(inode))
+ return;
if (inode->i_data.nrpages)
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3b534e5..6955c5a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2144,6 +2144,7 @@ extern ino_t iunique(struct super_block *, ino_t);
extern int inode_needs_sync(struct inode *inode);
extern void generic_delete_inode(struct inode *inode);
extern void generic_drop_inode(struct inode *inode);
+extern int generic_detach_inode(struct inode *inode);

extern struct inode *ilookup5_nowait(struct super_block *sb,
unsigned long hashval, int (*test)(struct inode *, void *),
--
1.6.0.2


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