From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Price <anprice@redhat.com>
Date: Fri, 19 Jan 2018 10:47:00 +0000
Subject: [Cluster-devel] [PATCH v5 2/3] GFS2: Introduce new
 gfs2_log_header_v2
In-Reply-To: <20180118160445.12732-3-agruenba@redhat.com>
References: <20180118160445.12732-1-agruenba@redhat.com>
	<20180118160445.12732-3-agruenba@redhat.com>
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On 18/01/18 16:04, Andreas Gruenbacher wrote:
<snip>
> diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
> index c27cbcebfe88..a2eb13c04591 100644
> --- a/fs/gfs2/log.c
> +++ b/fs/gfs2/log.c
> @@ -14,6 +14,7 @@
>   #include <linux/buffer_head.h>
>   #include <linux/gfs2_ondisk.h>
>   #include <linux/crc32.h>
> +#include <linux/crc32c.h>
>   #include <linux/delay.h>
>   #include <linux/kthread.h>
>   #include <linux/freezer.h>
> @@ -653,20 +654,25 @@ void gfs2_write_revokes(struct gfs2_sbd *sdp)
>   /**
>    * write_log_header - Write a journal log header buffer at sd_log_flush_head
>    * @sdp: The GFS2 superblock
> + * @jd: journal descriptor of the journal to which we are writing
>    * @seq: sequence number
>    * @tail: tail of the log
> - * @flags: log header flags
> + * @flags: log header flags GFS2_LOG_HEAD_*
>    * @op_flags: flags to pass to the bio
>    *
>    * Returns: the initialized log buffer descriptor
>    */
>   
> -void gfs2_write_log_header(struct gfs2_sbd *sdp, u64 seq, u32 tail,
> -			   u32 flags, int op_flags)
> +void gfs2_write_log_header(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
> +			   u64 seq, u32 tail, u32 flags, int op_flags)
>   {
>   	struct gfs2_log_header *lh;
> -	u32 hash;
> +	u32 hash, crc;
>   	struct page *page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
> +	struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
> +	struct timespec64 tv;
> +	struct super_block *sb = sdp->sd_vfs;
> +	u64 addr;
>   
>   	lh = page_address(page);
>   	clear_page(lh);
> @@ -680,10 +686,39 @@ void gfs2_write_log_header(struct gfs2_sbd *sdp, u64 seq, u32 tail,
>   	lh->lh_flags = cpu_to_be32(flags);
>   	lh->lh_tail = cpu_to_be32(tail);
>   	lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);
> -	hash = ~crc32(~0, lh, sizeof(*lh));
> +	hash = ~crc32(~0, lh, LH_V1_SIZE);
>   	lh->lh_hash = cpu_to_be32(hash);
>   
> -	gfs2_log_write_page(sdp, page);
> +	tv = current_kernel_time64();
> +	lh->lh_nsec = cpu_to_be32(tv.tv_nsec);
> +	lh->lh_sec = cpu_to_be64(tv.tv_sec);
> +	addr = gfs2_log_bmap(sdp);
> +	lh->lh_addr = cpu_to_be64(addr);
> +	lh->lh_jinode = cpu_to_be64(GFS2_I(jd->jd_inode)->i_no_addr);
> +
> +	/* We may only write local statfs, quota, etc., when writing to our
> +	   own journal. The values are left 0 when recovering a journal
> +	   different from our own. */
> +	if (!(flags & GFS2_LOG_HEAD_RECOVERY)) {
> +		lh->lh_statfs_addr =
> +			cpu_to_be64(GFS2_I(sdp->sd_sc_inode)->i_no_addr);
> +		lh->lh_quota_addr =
> +			cpu_to_be64(GFS2_I(sdp->sd_qc_inode)->i_no_addr);
> +
> +		spin_lock(&sdp->sd_statfs_spin);
> +		lh->lh_local_total = cpu_to_be64(l_sc->sc_total);
> +		lh->lh_local_free = cpu_to_be64(l_sc->sc_free);
> +		lh->lh_local_dinodes = cpu_to_be64(l_sc->sc_dinodes);
> +		spin_unlock(&sdp->sd_statfs_spin);
> +	}
> +
> +	BUILD_BUG_ON(offsetof(struct gfs2_log_header, lh_crc) != LH_V1_SIZE);
> +
> +	crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
> +		     sb->s_blocksize - LH_V1_SIZE - 4);
> +	lh->lh_crc = cpu_to_be32(crc);

This seems to be at odds with the field comment:

 > +	__be32 lh_crc;		/* crc32 of whole block with this field 0 */

Is it really just CRCing the block from lh_crc + 4 onwards?

Andy