"Stephen C. Tweedie" wrote:
>
> Hi,
>
> On Wed, 12 May 1999 12:30:27 +0200, "Manfred Spraul"
> <masp0008@stud.uni-sb.de> said:
>
> > There is another problem with this line:
> > set_blocksize() also means that the previous block size
> > doesn't work anymore:
> > if you accidentially enter 'swapon /dev/hda1' (my root drive)
> > instead of 'swapon /dev/hda3', then you have to fsck:
>
> Yep, it would make perfect sense to move the set_blocksize to be after
> the EBUSY check.
Unfortunately that doesn't solve the problem:
The current EBUSY check checks that the partition is not used as a
swap partition, it doesn't check the VFS, and it doesn't check
whether the RAID driver uses the volume.
I've attached an old patch (vs.2.2.6):
I've send that patch to linux-kernel@vger, Alan (..wait until Linus
returns from vacation..), Linus (no reply).
The patch adds a bitmap to the block cache for EBUSY checks.
Actually, we can use this bitmap for other bits if we use devfs and
dynamic MAJOR/MINOR codes:
we must replace all 'MAJOR==LOOP', 'MAJOR==IDE' etc. if we want to
support dynamic block device MAJOR/MINOR's.
Additionally, we save 6-8 kB kernel memory. (ro_bits was an 8 kB
static array).
If you think that the patch is usefull, then I'll make a new patch
vs 2.3.0, otherwise I'll wait until devfs is added, and I'll
try to write a larger patch (dynamic MAJOR/MINOR for block cache)
that includes this one.
-- Manfred --------------B11A5DF7FFF27357F3C3C859 Content-Type: text/plain; charset=us-ascii; name="patch_busy-2.2.6" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="patch_busy-2.2.6"diff -r -u -P -x CVS -x *,v 2.2.6/drivers/block/ll_rw_blk.c current/drivers/block/ll_rw_blk.c --- 2.2.6/drivers/block/ll_rw_blk.c Wed Mar 31 00:56:57 1999 +++ current/drivers/block/ll_rw_blk.c Thu Apr 22 18:02:20 1999 @@ -16,6 +16,7 @@ #include <linux/config.h> #include <linux/locks.h> #include <linux/mm.h> +#include <linux/slab.h> #include <linux/init.h> #include <asm/system.h> @@ -241,8 +242,24 @@ } /* RO fail safe mechanism */ +/* device busy: (C) Manfred Spraul masp0008@stud.uni-sb.de */ -static long ro_bits[MAX_BLKDEV][8]; +struct kdev_bits { + unsigned char ro_bits[(1U << MINORBITS)/8]; + unsigned char busy_bits[(1U << MINORBITS)/8]; +}; + +static struct kdev_bits* kdev_info[MAX_BLKDEV] = { NULL, NULL }; + +#define ALLOC_KDEV_BITS(major) \ + if (kdev_info[major] == NULL) { \ + kdev_info[major] = kmalloc(sizeof(struct kdev_bits),GFP_KERNEL); \ + if(kdev_info[major] == NULL) { \ + printk("ALLOC_KDEV_BITS() failed due to ENOMEM.\n"); \ + return; \ + } \ + memset(kdev_info[major],0,sizeof(struct kdev_bits)); \ + } int is_read_only(kdev_t dev) { @@ -251,7 +268,8 @@ major = MAJOR(dev); minor = MINOR(dev); if (major < 0 || major >= MAX_BLKDEV) return 0; - return ro_bits[major][minor >> 5] & (1 << (minor & 31)); + if (kdev_info[major] == NULL) return 0; + return kdev_info[major]->ro_bits[minor >> 3] & (1 << (minor & 7)); } void set_device_ro(kdev_t dev,int flag) @@ -261,10 +279,39 @@ major = MAJOR(dev); minor = MINOR(dev); if (major < 0 || major >= MAX_BLKDEV) return; - if (flag) ro_bits[major][minor >> 5] |= 1 << (minor & 31); - else ro_bits[major][minor >> 5] &= ~(1 << (minor & 31)); + ALLOC_KDEV_BITS(major) + if (flag) + kdev_info[major]->ro_bits[minor >> 3] |= 1 << (minor & 7); + else + kdev_info[major]->ro_bits[minor >> 3] &= ~(1 << (minor & 7)); +} + +int is_device_busy(kdev_t dev) +{ + int minor,major; + + major = MAJOR(dev); + minor = MINOR(dev); + if (major < 0 || major >= MAX_BLKDEV) return 0; + if (kdev_info[major] == NULL) return 0; + return kdev_info[major]->busy_bits[minor >> 3] & (1 << (minor & 7)); } +void set_device_busy(kdev_t dev,int flag) +{ + int minor,major; + + major = MAJOR(dev); + minor = MINOR(dev); + if (major < 0 || major >= MAX_BLKDEV) return; + ALLOC_KDEV_BITS(major) + if (flag) + kdev_info[major]->busy_bits[minor >> 3] |= 1 << (minor & 7); + else + kdev_info[major]->busy_bits[minor >> 3] &= ~(1 << (minor & 7)); +} + + static inline void drive_stat_acct(int cmd, unsigned long nr_sectors, short disk_index) { @@ -731,7 +778,6 @@ req->rq_status = RQ_INACTIVE; req->next = NULL; } - memset(ro_bits,0,sizeof(ro_bits)); memset(max_readahead, 0, sizeof(max_readahead)); memset(max_sectors, 0, sizeof(max_sectors)); #ifdef CONFIG_AMIGA_Z2RAM diff -r -u -P -x CVS -x *,v 2.2.6/fs/super.c current/fs/super.c --- 2.2.6/fs/super.c Tue Apr 20 13:41:57 1999 +++ current/fs/super.c Thu Apr 22 18:02:20 1999 @@ -131,6 +131,7 @@ vfsmnttail->mnt_next = lptr; vfsmnttail = lptr; } + set_device_busy(sb->s_dev,1); out: return lptr; } @@ -165,6 +166,8 @@ kfree(tofree->mnt_devname); kfree(tofree->mnt_dirname); kfree_s(tofree, sizeof(struct vfsmount)); + + set_device_busy(dev,0); } int register_filesystem(struct file_system_type * fs) @@ -873,6 +876,8 @@ if (dir_d->d_covers != dir_d) goto dput_and_out; + if (is_device_busy(dev)) + goto dput_and_out; /* * Note: If the superblock already exists, * read_super just does a get_super(). diff -r -u -P -x CVS -x *,v 2.2.6/include/linux/fs.h current/include/linux/fs.h --- 2.2.6/include/linux/fs.h Tue Apr 20 13:41:58 1999 +++ current/include/linux/fs.h Thu Apr 22 18:02:20 1999 @@ -839,6 +839,8 @@ extern struct buffer_head * find_buffer(kdev_t dev, int block, int size); extern void ll_rw_block(int, int, struct buffer_head * bh[]); extern int is_read_only(kdev_t); +extern int is_device_busy(kdev_t); +extern void set_device_busy(kdev_t dev, int flag); extern void __brelse(struct buffer_head *); extern inline void brelse(struct buffer_head *buf) { diff -r -u -P -x CVS -x *,v 2.2.6/kernel/ksyms.c current/kernel/ksyms.c --- 2.2.6/kernel/ksyms.c Wed Mar 31 00:56:57 1999 +++ current/kernel/ksyms.c Thu Apr 22 18:02:20 1999 @@ -47,7 +47,7 @@ #endif extern char *get_options(char *str, int *ints); -extern void set_device_ro(kdev_t dev,int flag); +extern void set_device_ro(kdev_t dev, int flag); extern struct file_operations * get_blkfops(unsigned int); extern int blkdev_release(struct inode * inode); #if !defined(CONFIG_NFSD) && defined(CONFIG_NFSD_MODULE) @@ -209,6 +209,8 @@ EXPORT_SYMBOL(blk_dev); EXPORT_SYMBOL(is_read_only); EXPORT_SYMBOL(set_device_ro); +EXPORT_SYMBOL(is_device_busy); +EXPORT_SYMBOL(set_device_busy); EXPORT_SYMBOL(bmap); EXPORT_SYMBOL(sync_dev); EXPORT_SYMBOL(get_blkfops); diff -r -u -P -x CVS -x *,v 2.2.6/mm/swapfile.c current/mm/swapfile.c --- 2.2.6/mm/swapfile.c Wed Mar 31 00:56:57 1999 +++ current/mm/swapfile.c Thu Apr 22 18:02:20 1999 @@ -414,6 +414,7 @@ filp.f_op->release(dentry->d_inode,&filp); filp.f_op->release(dentry->d_inode,&filp); } + set_device_busy(p->swap_device,0); } dput(dentry); @@ -531,6 +532,10 @@ if (S_ISBLK(swap_dentry->d_inode->i_mode)) { p->swap_device = swap_dentry->d_inode->i_rdev; + if(is_device_busy(p->swap_device)) { + error = -EBUSY; + goto bad_swap; + } set_blocksize(p->swap_device, PAGE_SIZE); filp.f_dentry = swap_dentry; @@ -686,6 +691,8 @@ swap_info[prev].next = p - swap_info; } error = 0; + if(p->swap_device != 0) + set_device_busy(p->swap_device,1); goto out; bad_swap: if(filp.f_op && filp.f_op->release)
--------------B11A5DF7FFF27357F3C3C859--
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