Linux-ext4 Archive on
 help / color / Atom feed
From: Jan Kara <>
To: Ted Tso <>
Cc: <>, Jan Kara <>
Subject: [PATCH] resize2fs: Make minimum size estimates more reliable for mounted fs
Date: Fri, 18 Oct 2019 14:50:59 +0200
Message-ID: <> (raw)

Currently, the estimate of minimum filesystem size is using free blocks
counter in the superblock. The counter generally doesn't get updated
while the filesystem is mounted and thus the estimate is very unreliable
for a mounted filesystem. For some usecases such as automated
partitioning proposal to the user it is desirable that the estimate of
minimum filesystem size is reasonably accurate even for a mounted
filesystem. So use group descriptor counters of free blocks for the
estimate of minimum filesystem size. These get updated together with
block being allocated and so the resulting estimate is more accurate.

Signed-off-by: Jan Kara <>
 resize/resize2fs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index c2e10471bfd1..8a3d08db19f3 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -2926,11 +2926,11 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 	/* calculate how many blocks are needed for data */
-	data_needed = ext2fs_blocks_count(fs->super) -
-		ext2fs_free_blocks_count(fs->super);
-	for (grp = 0; grp < fs->group_desc_count; grp++)
+	data_needed = ext2fs_blocks_count(fs->super);
+	for (grp = 0; grp < fs->group_desc_count; grp++) {
 		data_needed -= calc_group_overhead(fs, grp, old_desc_blocks);
+		data_needed -= ext2fs_bg_free_blocks_count(fs, grp);
+	}
 	if (flags & RESIZE_DEBUG_MIN_CALC)
 		printf("fs requires %llu data blocks.\n", data_needed);

             reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-18 12:50 Jan Kara [this message]
2019-11-10 13:14 ` Theodore Y. Ts'o

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ext4 Archive on

Archives are clonable:
	git clone --mirror linux-ext4/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-ext4 linux-ext4/ \
	public-inbox-index linux-ext4

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone