ext2fs crash in -current (r218056)

[Doug Barton]

I haven't had a chance to test this patch yet, but John's did not work 
(sorry):

http://dougbarton.us/ext2fs-crash-dump-2.jpg

No actual dump this time either.

I'm happy to test the patch below on Thursday if there is consensus that 
it will work.


Doug


On 02/01/2011 17:42, Aditya Sarawgi wrote:
> Hi John,
>
> I can see what you are saying. Can't we check
> the number of free blocks in the given cg without
> locking the fs.
> This way
>
>    		EXT2_LOCK(ump);
>    		return (0);
>    	}
>   +	if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0) {
>   +		/*
>   +		 * Another thread allocated the last block in this
>   +		 * group while we were waiting for the buffer.
>   +		 */
>   +		brelse(bp);
>   +		EXT2_LOCK(ump);
>   +		return (0);
>   +	}
>    	bbp = (char *)bp->b_data;
>
>    	if (dtog(fs, bpref) != cg)
>
>
> UFS is doing something similar
>
> static ufs2_daddr_t
> ffs_alloccg(ip, cg, bpref, size, rsize)
>    struct inode *ip;
>    u_int cg;
>    ufs2_daddr_t bpref;
>    int size;
>    int rsize;
> {
>    struct fs *fs;
>    struct cg *cgp;
>    struct buf *bp;
>    struct ufsmount *ump;
>    ufs1_daddr_t bno;
>    ufs2_daddr_t blkno;
>    int i, allocsiz, error, frags;
>    u_int8_t *blksfree;
>
>    ump = ip->i_ump;
>    fs = ip->i_fs;
>    if (fs->fs_cs(fs, cg).cs_nbfree == 0&&  size == fs->fs_bsize)
>      return (0);
>    UFS_UNLOCK(ump);
>    error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
>      (int)fs->fs_cgsize, NOCRED,&bp);
>    if (error)
>      goto fail;
>    cgp = (struct cg *)bp->b_data;
>    if (!cg_chkmagic(cgp) ||
>        (cgp->cg_cs.cs_nbfree == 0&&  size == fs->fs_bsize))
>      goto fail;
>> Please try this:
>>
>> Index: ext2_alloc.c
>> ===================================================================
>> --- ext2_alloc.c	(revision 218175)
>> +++ ext2_alloc.c	(working copy)
>> @@ -650,6 +650,18 @@
>>   		EXT2_LOCK(ump);
>>   		return (0);
>>   	}
>> +	EXT2_LOCK(ump);
>> +	if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0) {
>> +		/*
>> +		 * Another thread allocated the last block in this
>> +		 * group while we were waiting for the buffer.
>> +		 */
>> +		EXT2_UNLOCK(ump);
>> +		brelse(bp);
>> +		EXT2_LOCK(ump);
>> +		return (0);
>> +	}
>> +	EXT2_UNLOCK(ump);
>>   	bbp = (char *)bp->b_data;
>>
>>   	if (dtog(fs, bpref) != cg)
>> @@ -776,6 +788,18 @@
>>   		EXT2_LOCK(ump);
>>   		return (0);
>>   	}
>> +	EXT2_LOCK(ump);
>> +	if (fs->e2fs_gd[cg].ext2bgd_nifree == 0) {
>> +		/*
>> +		 * Another thread allocated the last i-node in this
>> +		 * group while we were waiting for the buffer.
>> +		 */
>> +		EXT2_UNLOCK(ump);
>> +		brelse(bp);
>> +		EXT2_LOCK(ump);
>> +		return (0);
>> +	}
>> +	EXT2_UNLOCK(ump);	
>>   	ibp = (char *)bp->b_data;
>>   	if (ipref) {
>>   		ipref %= fs->e2fs->e2fs_ipg;
>
> --
> Aditya Sarawgi
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