From: Theodore Ts'o <tytso@mit.edu>
Date: Tue, 20 Jan 2009 05:46:06 +0000 (-0500)
Subject: resize2fs: Reserve some extra space for -P/-M for ext4 filesystems
X-Git-Tag: v1.41.4~19
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=793a04a0719d5688a0033e4bda3cf267f57ea760;p=tools%2Fe2fsprogs.git

resize2fs: Reserve some extra space for -P/-M for ext4 filesystems

Some extra blocks may be needed to expand some extent allocation trees
while we are shrinking the filesystem.  We don't know exactly how
much, so we use a hueristic.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index df4dac7..b7c42ce 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -1954,5 +1954,13 @@ blk_t calculate_minimum_resize_size(ext2_filsys fs)
 	blks_needed = (groups-1) * EXT2_BLOCKS_PER_GROUP(fs->super);
 	blks_needed += overhead;
 
+	/*
+	 * We need to reserve a few extra blocks if extents are
+	 * enabled, in case we need to grow the extent tree.  The more
+	 * we shrink the file system, the more space we need.
+	 */
+	if (fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_EXTENTS)
+		blks_needed += (fs->super->s_blocks_count - blks_needed)/500;
+
 	return blks_needed;
 }