Revision 737449236240e30a7bbe99f4d5586b8ed1416763 authored by Mel Gorman on 31 July 2012, 23:45:20 UTC, committed by Linus Torvalds on 01 August 2012, 01:42:48 UTC
Commit b3a27d ("swap: Add swap slot free callback to block_device_operations") dereferences p->bdev->bd_disk but this is a NULL dereference if using swap-over-NFS. This patch checks SWP_BLKDEV on the swap_info_struct before dereferencing. With reference to this callback, Christoph Hellwig stated "Please just remove the callback entirely. It has no user outside the staging tree and was added clearly against the rules for that staging tree". This would also be my preference but there was not an obvious way of keeping zram in staging/ happy. Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bitmap.c
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <asm/div64.h>
#include "omfs.h"
unsigned long omfs_count_free(struct super_block *sb)
{
unsigned int i;
unsigned long sum = 0;
struct omfs_sb_info *sbi = OMFS_SB(sb);
int nbits = sb->s_blocksize * 8;
for (i = 0; i < sbi->s_imap_size; i++)
sum += nbits - bitmap_weight(sbi->s_imap[i], nbits);
return sum;
}
/*
* Counts the run of zero bits starting at bit up to max.
* It handles the case where a run might spill over a buffer.
* Called with bitmap lock.
*/
static int count_run(unsigned long **addr, int nbits,
int addrlen, int bit, int max)
{
int count = 0;
int x;
for (; addrlen > 0; addrlen--, addr++) {
x = find_next_bit(*addr, nbits, bit);
count += x - bit;
if (x < nbits || count > max)
return min(count, max);
bit = 0;
}
return min(count, max);
}
/*
* Sets or clears the run of count bits starting with bit.
* Called with bitmap lock.
*/
static int set_run(struct super_block *sb, int map,
int nbits, int bit, int count, int set)
{
int i;
int err;
struct buffer_head *bh;
struct omfs_sb_info *sbi = OMFS_SB(sb);
err = -ENOMEM;
bh = sb_bread(sb, clus_to_blk(sbi, sbi->s_bitmap_ino) + map);
if (!bh)
goto out;
for (i = 0; i < count; i++, bit++) {
if (bit >= nbits) {
bit = 0;
map++;
mark_buffer_dirty(bh);
brelse(bh);
bh = sb_bread(sb,
clus_to_blk(sbi, sbi->s_bitmap_ino) + map);
if (!bh)
goto out;
}
if (set) {
set_bit(bit, sbi->s_imap[map]);
set_bit(bit, (unsigned long *)bh->b_data);
} else {
clear_bit(bit, sbi->s_imap[map]);
clear_bit(bit, (unsigned long *)bh->b_data);
}
}
mark_buffer_dirty(bh);
brelse(bh);
err = 0;
out:
return err;
}
/*
* Tries to allocate exactly one block. Returns true if successful.
*/
int omfs_allocate_block(struct super_block *sb, u64 block)
{
struct buffer_head *bh;
struct omfs_sb_info *sbi = OMFS_SB(sb);
int bits_per_entry = 8 * sb->s_blocksize;
unsigned int map, bit;
int ret = 0;
u64 tmp;
tmp = block;
bit = do_div(tmp, bits_per_entry);
map = tmp;
mutex_lock(&sbi->s_bitmap_lock);
if (map >= sbi->s_imap_size || test_and_set_bit(bit, sbi->s_imap[map]))
goto out;
if (sbi->s_bitmap_ino > 0) {
bh = sb_bread(sb, clus_to_blk(sbi, sbi->s_bitmap_ino) + map);
if (!bh)
goto out;
set_bit(bit, (unsigned long *)bh->b_data);
mark_buffer_dirty(bh);
brelse(bh);
}
ret = 1;
out:
mutex_unlock(&sbi->s_bitmap_lock);
return ret;
}
/*
* Tries to allocate a set of blocks. The request size depends on the
* type: for inodes, we must allocate sbi->s_mirrors blocks, and for file
* blocks, we try to allocate sbi->s_clustersize, but can always get away
* with just one block.
*/
int omfs_allocate_range(struct super_block *sb,
int min_request,
int max_request,
u64 *return_block,
int *return_size)
{
struct omfs_sb_info *sbi = OMFS_SB(sb);
int bits_per_entry = 8 * sb->s_blocksize;
int ret = 0;
int i, run, bit;
mutex_lock(&sbi->s_bitmap_lock);
for (i = 0; i < sbi->s_imap_size; i++) {
bit = 0;
while (bit < bits_per_entry) {
bit = find_next_zero_bit(sbi->s_imap[i], bits_per_entry,
bit);
if (bit == bits_per_entry)
break;
run = count_run(&sbi->s_imap[i], bits_per_entry,
sbi->s_imap_size-i, bit, max_request);
if (run >= min_request)
goto found;
bit += run;
}
}
ret = -ENOSPC;
goto out;
found:
*return_block = i * bits_per_entry + bit;
*return_size = run;
ret = set_run(sb, i, bits_per_entry, bit, run, 1);
out:
mutex_unlock(&sbi->s_bitmap_lock);
return ret;
}
/*
* Clears count bits starting at a given block.
*/
int omfs_clear_range(struct super_block *sb, u64 block, int count)
{
struct omfs_sb_info *sbi = OMFS_SB(sb);
int bits_per_entry = 8 * sb->s_blocksize;
u64 tmp;
unsigned int map, bit;
int ret;
tmp = block;
bit = do_div(tmp, bits_per_entry);
map = tmp;
if (map >= sbi->s_imap_size)
return 0;
mutex_lock(&sbi->s_bitmap_lock);
ret = set_run(sb, map, bits_per_entry, bit, count, 0);
mutex_unlock(&sbi->s_bitmap_lock);
return ret;
}
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