git-holes

Committed for glibc 2.32

commit 3f6e4fc4542b5b881906bf2f83eb4b8359b0dcd4
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Thu Jun 4 20:52:19 2020 +0200

    support: Fix detecting hole support on >2KB-block filesystems

    When detecting hole support, we write at 16MiB, and filesystems will
    typically need two levels of data to record that. On filesystems with
    8KB block, the two indirection blocks will require a total of 16KB
    overhead, thus 32 512-byte sectors.

    Spotted on GNU/Hurd with a 4KB blocks filesystem, but also happens on Linux
    with 4KB or 8KB blocks filesystems.

    * support/support_descriptor_supports_holes.c
    (support_descriptor_supports_holes): Set block_headroom to 32.

Gbp-Pq: Topic hurd-i386
Gbp-Pq: Name git-holes.diff

diff --git a/support/support_descriptor_supports_holes.c b/support/support_descriptor_supports_holes.c
index fc2aa76f10aaa6dd69c3719914e69de8ec32039b..d3d5d3a93818549bb96af95b897e4d6064037439 100644 (file)
--- a/support/support_descriptor_supports_holes.c
+++ b/support/support_descriptor_supports_holes.c
@@ -34,8 +34,10 @@ support_descriptor_supports_holes (int fd)
       write_offset = 16 * 1024 * 1024,
 
       /* Our write may add this number of additional blocks (see
-         block_limit below).  */
-      block_headroom = 8,
+         block_limit below): writing at offset 16M can require two data block
+         indirections, each of which can be as large as 8KB on ext2, thus 32
+         512B sectors.  */
+      block_headroom = 32,
     };
 
   struct stat64 st;