[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 2c01a90..3e36107 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -16,6 +16,22 @@
#include <asm/scatterlist.h>
+#ifdef CONFIG_LBD
+# include <asm/div64.h>
+# define sector_div(a, b) do_div(a, b)
+#else
+# define sector_div(n, b)( \
+{ \
+ int _res; \
+ _res = (n) % (b); \
+ (n) /= (b); \
+ _res; \
+} \
+)
+#endif
+
+#ifdef CONFIG_BLOCK
+
struct scsi_ioctl_command;
struct request_queue;
@@ -818,24 +834,30 @@
int kblockd_schedule_work(struct work_struct *work);
void kblockd_flush(void);
-#ifdef CONFIG_LBD
-# include <asm/div64.h>
-# define sector_div(a, b) do_div(a, b)
-#else
-# define sector_div(n, b)( \
-{ \
- int _res; \
- _res = (n) % (b); \
- (n) /= (b); \
- _res; \
-} \
-)
-#endif
-
#define MODULE_ALIAS_BLOCKDEV(major,minor) \
MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
#define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
MODULE_ALIAS("block-major-" __stringify(major) "-*")
+#else /* CONFIG_BLOCK */
+/*
+ * stubs for when the block layer is configured out
+ */
+#define buffer_heads_over_limit 0
+
+static inline long blk_congestion_wait(int rw, long timeout)
+{
+ return timeout;
+}
+
+static inline long nr_blockdev_pages(void)
+{
+ return 0;
+}
+
+static inline void exit_io_context(void) {}
+
+#endif /* CONFIG_BLOCK */
+
#endif
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 64b508e..131ffd3 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -14,6 +14,8 @@
#include <linux/wait.h>
#include <asm/atomic.h>
+#ifdef CONFIG_BLOCK
+
enum bh_state_bits {
BH_Uptodate, /* Contains valid data */
BH_Dirty, /* Is dirty */
@@ -301,4 +303,18 @@
}
extern int __set_page_dirty_buffers(struct page *page);
+
+#else /* CONFIG_BLOCK */
+
+static inline void buffer_init(void) {}
+static inline int try_to_free_buffers(struct page *page) { return 1; }
+static inline int sync_blockdev(struct block_device *bdev) { return 0; }
+static inline int inode_has_buffers(struct inode *inode) { return 0; }
+static inline void invalidate_inode_buffers(struct inode *inode) {}
+static inline int remove_inode_buffers(struct inode *inode) { return 1; }
+static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
+static inline void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) {}
+
+
+#endif /* CONFIG_BLOCK */
#endif /* _LINUX_BUFFER_HEAD_H */
diff --git a/include/linux/compat_ioctl.h b/include/linux/compat_ioctl.h
index 98d40e0..d61ef59 100644
--- a/include/linux/compat_ioctl.h
+++ b/include/linux/compat_ioctl.h
@@ -90,6 +90,7 @@
COMPATIBLE_IOCTL(FDFMTTRK)
COMPATIBLE_IOCTL(FDRAWCMD)
/* 0x12 */
+#ifdef CONFIG_BLOCK
COMPATIBLE_IOCTL(BLKRASET)
COMPATIBLE_IOCTL(BLKROSET)
COMPATIBLE_IOCTL(BLKROGET)
@@ -103,6 +104,7 @@
COMPATIBLE_IOCTL(BLKTRACETEARDOWN)
ULONG_IOCTL(BLKRASET)
ULONG_IOCTL(BLKFRASET)
+#endif
/* RAID */
COMPATIBLE_IOCTL(RAID_VERSION)
COMPATIBLE_IOCTL(GET_ARRAY_INFO)
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 9c5a04f..b3370ef 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -3,6 +3,8 @@
#include <linux/percpu.h>
+#ifdef CONFIG_BLOCK
+
typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
struct bio *);
@@ -203,4 +205,5 @@
__val; \
})
+#endif /* CONFIG_BLOCK */
#endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b73a475..5baf3a1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1482,6 +1482,7 @@
extern void putname(const char *name);
#endif
+#ifdef CONFIG_BLOCK
extern int register_blkdev(unsigned int, const char *);
extern int unregister_blkdev(unsigned int, const char *);
extern struct block_device *bdget(dev_t);
@@ -1490,11 +1491,15 @@
extern void bdput(struct block_device *);
extern struct block_device *open_by_devnum(dev_t, unsigned);
extern struct block_device *open_partition_by_devnum(dev_t, unsigned);
-extern const struct file_operations def_blk_fops;
extern const struct address_space_operations def_blk_aops;
+#else
+static inline void bd_forget(struct inode *inode) {}
+#endif
+extern const struct file_operations def_blk_fops;
extern const struct file_operations def_chr_fops;
extern const struct file_operations bad_sock_fops;
extern const struct file_operations def_fifo_fops;
+#ifdef CONFIG_BLOCK
extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
extern int blkdev_ioctl(struct inode *, struct file *, unsigned, unsigned long);
extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
@@ -1510,6 +1515,7 @@
#define bd_claim_by_disk(bdev, holder, disk) bd_claim(bdev, holder)
#define bd_release_from_disk(bdev, disk) bd_release(bdev)
#endif
+#endif
/* fs/char_dev.c */
#define CHRDEV_MAJOR_HASH_SIZE 255
@@ -1523,14 +1529,19 @@
extern void chrdev_show(struct seq_file *,off_t);
/* fs/block_dev.c */
-#define BLKDEV_MAJOR_HASH_SIZE 255
#define BDEVNAME_SIZE 32 /* Largest string for a blockdev identifier */
+
+#ifdef CONFIG_BLOCK
+#define BLKDEV_MAJOR_HASH_SIZE 255
extern const char *__bdevname(dev_t, char *buffer);
extern const char *bdevname(struct block_device *bdev, char *buffer);
extern struct block_device *lookup_bdev(const char *);
extern struct block_device *open_bdev_excl(const char *, int, void *);
extern void close_bdev_excl(struct block_device *);
extern void blkdev_show(struct seq_file *,off_t);
+#else
+#define BLKDEV_MAJOR_HASH_SIZE 0
+#endif
extern void init_special_inode(struct inode *, umode_t, dev_t);
@@ -1544,6 +1555,7 @@
extern int fs_may_remount_ro(struct super_block *);
+#ifdef CONFIG_BLOCK
/*
* return READ, READA, or WRITE
*/
@@ -1555,9 +1567,10 @@
#define bio_data_dir(bio) ((bio)->bi_rw & 1)
extern int check_disk_change(struct block_device *);
-extern int invalidate_inodes(struct super_block *);
extern int __invalidate_device(struct block_device *);
extern int invalidate_partition(struct gendisk *, int);
+#endif
+extern int invalidate_inodes(struct super_block *);
unsigned long invalidate_mapping_pages(struct address_space *mapping,
pgoff_t start, pgoff_t end);
unsigned long invalidate_inode_pages(struct address_space *mapping);
@@ -1590,7 +1603,9 @@
extern void emergency_remount(void);
extern int do_remount_sb(struct super_block *sb, int flags,
void *data, int force);
+#ifdef CONFIG_BLOCK
extern sector_t bmap(struct inode *, sector_t);
+#endif
extern int notify_change(struct dentry *, struct iattr *);
extern int permission(struct inode *, int, struct nameidata *);
extern int generic_permission(struct inode *, int,
@@ -1673,9 +1688,11 @@
extern struct file * get_empty_filp(void);
extern void file_move(struct file *f, struct list_head *list);
extern void file_kill(struct file *f);
+#ifdef CONFIG_BLOCK
struct bio;
extern void submit_bio(int, struct bio *);
extern int bdev_read_only(struct block_device *);
+#endif
extern int set_blocksize(struct block_device *, int);
extern int sb_set_blocksize(struct super_block *, int);
extern int sb_min_blocksize(struct super_block *, int);
@@ -1756,6 +1773,7 @@
actor);
}
+#ifdef CONFIG_BLOCK
ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
struct block_device *bdev, const struct iovec *iov, loff_t offset,
unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io,
@@ -1793,6 +1811,7 @@
return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
nr_segs, get_block, end_io, DIO_OWN_LOCKING);
}
+#endif
extern const struct file_operations generic_ro_fops;
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index e4af57e..41f276f 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -11,6 +11,8 @@
#include <linux/types.h>
+#ifdef CONFIG_BLOCK
+
enum {
/* These three have identical behaviour; use the second one if DOS FDISK gets
confused about extended/logical partitions starting past cylinder 1023. */
@@ -420,3 +422,5 @@
#endif
#endif
+
+#endif
diff --git a/include/linux/mpage.h b/include/linux/mpage.h
index 517c098..cc5fb75 100644
--- a/include/linux/mpage.h
+++ b/include/linux/mpage.h
@@ -9,6 +9,7 @@
* (And no, it doesn't do the #ifdef __MPAGE_H thing, and it doesn't do
* nested includes. Get it right in the .c file).
*/
+#ifdef CONFIG_BLOCK
struct writeback_control;
typedef int (writepage_t)(struct page *page, struct writeback_control *wbc);
@@ -20,3 +21,5 @@
struct writeback_control *wbc, get_block_t get_block);
int mpage_writepage(struct page *page, get_block_t *get_block,
struct writeback_control *wbc);
+
+#endif
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index eb3e547..c588709 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -53,6 +53,8 @@
#include <linux/raid/md_u.h>
#include <linux/raid/md_k.h>
+#ifdef CONFIG_MD
+
/*
* Different major versions are not compatible.
* Different minor versions are only downward compatible.
@@ -95,5 +97,6 @@
extern void md_update_sb(mddev_t * mddev);
+#endif /* CONFIG_MD */
#endif
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index d288902..920b94f 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -18,6 +18,8 @@
/* and dm-bio-list.h is not under include/linux because.... ??? */
#include "../../../drivers/md/dm-bio-list.h"
+#ifdef CONFIG_BLOCK
+
#define LEVEL_MULTIPATH (-4)
#define LEVEL_LINEAR (-1)
#define LEVEL_FAULTY (-5)
@@ -362,5 +364,6 @@
if (p) put_page(p);
}
+#endif /* CONFIG_BLOCK */
#endif
diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
index bbf6621..c247a282 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -6,7 +6,6 @@
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
-
#define MSG_SIMPLE_TAG 0x20
#define MSG_HEAD_TAG 0x21
#define MSG_ORDERED_TAG 0x22
@@ -14,6 +13,7 @@
#define SCSI_NO_TAG (-1) /* identify no tag in use */
+#ifdef CONFIG_BLOCK
/**
* scsi_get_tag_type - get the type of tag the device supports
@@ -144,4 +144,5 @@
return shost->bqt ? 0 : -ENOMEM;
}
+#endif /* CONFIG_BLOCK */
#endif /* _SCSI_SCSI_TCQ_H */