On 10/13/2017 03:12 AM, Ashish Samant wrote: > The first cluster group descriptor is not stored at the start of the group > but at an offset from the start. We need to take this into account while > doing fstrim on the first cluster group. Otherwise we will wrongly start > fstrim a few blocks after the desired start block and the range can cross > over into the next cluster group and zero out the group descriptor there. > This can cause filesytem corruption that cannot be fixed by fsck. > > Signed-off-by: Ashish Samant <ashish.sam...@oracle.com> > Cc: sta...@vger.kernel.org Looks good.
Reviewed-by: Junxiao Bi <junxiao...@oracle.com> > --- > fs/ocfs2/alloc.c | 24 ++++++++++++++++++------ > 1 file changed, 18 insertions(+), 6 deletions(-) > > diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c > index a177eae..addd7c5 100644 > --- a/fs/ocfs2/alloc.c > +++ b/fs/ocfs2/alloc.c > @@ -7304,13 +7304,24 @@ int ocfs2_truncate_inline(struct inode *inode, struct > buffer_head *di_bh, > > static int ocfs2_trim_extent(struct super_block *sb, > struct ocfs2_group_desc *gd, > - u32 start, u32 count) > + u64 group, u32 start, u32 count) > { > u64 discard, bcount; > + struct ocfs2_super *osb = OCFS2_SB(sb); > > bcount = ocfs2_clusters_to_blocks(sb, count); > - discard = le64_to_cpu(gd->bg_blkno) + > - ocfs2_clusters_to_blocks(sb, start); > + discard = ocfs2_clusters_to_blocks(sb, start); > + > + /* > + * For the first cluster group, the gd->bg_blkno is not at the start > + * of the group, but at an offset from the start. If we add it while > + * calculating discard for first group, we will wrongly start fstrim a > + * few blocks after the desried start block and the range can cross > + * over into the next cluster group. So, add it only if this is not > + * the first cluster group. > + */ > + if (group != osb->first_cluster_group_blkno) > + discard += le64_to_cpu(gd->bg_blkno); > > trace_ocfs2_trim_extent(sb, (unsigned long long)discard, bcount); > > @@ -7318,7 +7329,7 @@ static int ocfs2_trim_extent(struct super_block *sb, > } > > static int ocfs2_trim_group(struct super_block *sb, > - struct ocfs2_group_desc *gd, > + struct ocfs2_group_desc *gd, u64 group, > u32 start, u32 max, u32 minbits) > { > int ret = 0, count = 0, next; > @@ -7337,7 +7348,7 @@ static int ocfs2_trim_group(struct super_block *sb, > next = ocfs2_find_next_bit(bitmap, max, start); > > if ((next - start) >= minbits) { > - ret = ocfs2_trim_extent(sb, gd, > + ret = ocfs2_trim_extent(sb, gd, group, > start, next - start); > if (ret < 0) { > mlog_errno(ret); > @@ -7435,7 +7446,8 @@ int ocfs2_trim_fs(struct super_block *sb, struct > fstrim_range *range) > } > > gd = (struct ocfs2_group_desc *)gd_bh->b_data; > - cnt = ocfs2_trim_group(sb, gd, first_bit, last_bit, minlen); > + cnt = ocfs2_trim_group(sb, gd, group, > + first_bit, last_bit, minlen); > brelse(gd_bh); > gd_bh = NULL; > if (cnt < 0) { > _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel