[PATCH 1/4] blockdev: Don't use i_devices inode field

From: Jan Kara
Date: Wed Oct 22 2014 - 16:15:50 EST


Block devices use i_devices inode field to track all inodes that
reference a particular block device (through i_bdev field) so that this
reference can be removed when block device inode is being evicted from
memory. However we get a reference to the block device (in fact an inode
holding the block device structure) when setting up i_bdev in
bd_acquire() and we drop the reference only in bd_forget() when clearing
i_bdev. Thus inode holding block device structure can be evicted only
after all inodes referencing it are evicted and the whole excercise with
i_devices is pointless. Remove the i_devices handling.

Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/block_dev.c | 17 +++--------------
include/linux/fs.h | 1 -
2 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index cc9d4114cda0..493cd69df9a6 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -458,7 +458,6 @@ static void init_once(void *foo)

memset(bdev, 0, sizeof(*bdev));
mutex_init(&bdev->bd_mutex);
- INIT_LIST_HEAD(&bdev->bd_inodes);
INIT_LIST_HEAD(&bdev->bd_list);
#ifdef CONFIG_SYSFS
INIT_LIST_HEAD(&bdev->bd_holder_disks);
@@ -468,24 +467,14 @@ static void init_once(void *foo)
mutex_init(&bdev->bd_fsfreeze_mutex);
}

-static inline void __bd_forget(struct inode *inode)
-{
- list_del_init(&inode->i_devices);
- inode->i_bdev = NULL;
- inode->i_mapping = &inode->i_data;
-}
-
static void bdev_evict_inode(struct inode *inode)
{
struct block_device *bdev = &BDEV_I(inode)->bdev;
- struct list_head *p;
+
truncate_inode_pages_final(&inode->i_data);
invalidate_inode_buffers(inode); /* is it needed here? */
clear_inode(inode);
spin_lock(&bdev_lock);
- while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
- __bd_forget(list_entry(p, struct inode, i_devices));
- }
list_del_init(&bdev->bd_list);
spin_unlock(&bdev_lock);
}
@@ -645,7 +634,6 @@ static struct block_device *bd_acquire(struct inode *inode)
ihold(bdev->bd_inode);
inode->i_bdev = bdev;
inode->i_mapping = bdev->bd_inode->i_mapping;
- list_add(&inode->i_devices, &bdev->bd_inodes);
}
spin_unlock(&bdev_lock);
}
@@ -666,7 +654,8 @@ void bd_forget(struct inode *inode)
spin_lock(&bdev_lock);
if (!sb_is_blkdev_sb(inode->i_sb))
bdev = inode->i_bdev;
- __bd_forget(inode);
+ inode->i_bdev = NULL;
+ inode->i_mapping = &inode->i_data;
spin_unlock(&bdev_lock);

if (bdev)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a957d4366c24..d7fd7959a933 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -413,7 +413,6 @@ struct block_device {
struct inode * bd_inode; /* will die */
struct super_block * bd_super;
struct mutex bd_mutex; /* open/close mutex */
- struct list_head bd_inodes;
void * bd_claiming;
void * bd_holder;
int bd_holders;
--
1.8.1.4

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