mkfs: round log size down if rounding log start up causes overflow

If rounding the log start up to the next stripe unit would cause the log
to overrun the end of the AG, round the log size down by a stripe unit.
We already ensured that logblocks was small enough to fit inside the AG,
so the minor adjustment should suffice.

This can be reproduced with:
mkfs.xfs -dsu=44k,sw=1,size=300m,file,name=fsfile -m rmapbt=0
and:
mkfs.xfs -dsu=48k,sw=1,size=512m,file,name=fsfile -m rmapbt=0

Reported-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index b932acaae2f9a7d8fbf36b2d2ef535875ff4bbd2..01d2e8cadc4033cf313192b6e05d9c1ad9583532 100644 (file)
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -3234,6 +3234,15 @@ _("Due to stripe alignment, the internal log start (%lld) cannot be aligned\n"
        /* round up/down the log size now */
        align_log_size(cfg, sunit, max_logblocks);
 
+       /*
+        * If the end of the log has been rounded past the end of the AG,
+        * reduce logblocks by a stripe unit to try to get it back under EOAG.
+        */
+       if (!libxfs_verify_fsbext(mp, cfg->logstart, cfg->logblocks) &&
+           cfg->logblocks > sunit) {
+               cfg->logblocks -= sunit;
+       }
+
        /* check the aligned log still starts and ends in the same AG. */
        if (!libxfs_verify_fsbext(mp, cfg->logstart, cfg->logblocks)) {
                fprintf(stderr,