Commit 46866963 authored by Linus Torvalds's avatar Linus Torvalds

[REDO] ramdisk: separate the blockdev backing_dev_info from the hosted inodes

This re-applies the separation of the ramdisk blockdev inode
backing store and the files that live in the ramdisk.

Cset exclude: torvalds@ppc970.osdl.org|ChangeSet|20040521210025|21437
parent 520808bf
...@@ -310,22 +310,26 @@ static int rd_ioctl(struct inode *inode, struct file *file, ...@@ -310,22 +310,26 @@ static int rd_ioctl(struct inode *inode, struct file *file,
} }
/* /*
* The backing_dev_info is shared between files which are backed by the ramdisk * This is the backing_dev_info for the blockdev inode itself. It doesn't need
* inode and by the ramdisk inode itself. This is a bit unfortunate because * writeback and it does not contribute to dirty memory accounting.
* they really want separate semantics. The files *do* want full writeback
* and dirty-memory accounting treatment, whereas the ramdisk blockdev mapping
* wants neither.
*
* So we make things look like a regular blockdev and the cheat in various ways
* in the ramdisk inode's a_ops.
*/ */
static struct backing_dev_info rd_backing_dev_info = { static struct backing_dev_info rd_backing_dev_info = {
.ra_pages = 0, /* No readahead */ .ra_pages = 0, /* No readahead */
.memory_backed = 1, /* Does not contribute to dirty memory */ .memory_backed = 1, /* Does not contribute to dirty memory */
.unplug_io_fn = default_unplug_io_fn, .unplug_io_fn = default_unplug_io_fn,
}; };
/*
* This is the backing_dev_info for the files which live atop the ramdisk
* "device". These files do need writeback and they do contribute to dirty
* memory accounting.
*/
static struct backing_dev_info rd_file_backing_dev_info = {
.ra_pages = 0, /* No readahead */
.memory_backed = 0, /* Does contribute to dirty memory */
.unplug_io_fn = default_unplug_io_fn,
};
static int rd_open(struct inode *inode, struct file *filp) static int rd_open(struct inode *inode, struct file *filp)
{ {
unsigned unit = iminor(inode); unsigned unit = iminor(inode);
...@@ -343,6 +347,7 @@ static int rd_open(struct inode *inode, struct file *filp) ...@@ -343,6 +347,7 @@ static int rd_open(struct inode *inode, struct file *filp)
mapping = inode->i_mapping; mapping = inode->i_mapping;
mapping->a_ops = &ramdisk_aops; mapping->a_ops = &ramdisk_aops;
mapping->backing_dev_info = &rd_backing_dev_info; mapping->backing_dev_info = &rd_backing_dev_info;
bdev->bd_inode_backing_dev_info = &rd_file_backing_dev_info;
/* /*
* Deep badness. rd_blkdev_pagecache_IO() needs to allocate * Deep badness. rd_blkdev_pagecache_IO() needs to allocate
......
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