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| author | Akira Fujita <a-fujita@rs.jp.nec.com> | 2012-08-30 20:16:01 +0900 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-09-07 00:09:19 -0400 |
| commit | 321649c9f491c2012f5e1a20337fd276bc5290f0 (patch) | |
| tree | 61cef9847d0ce75c6db90757a8add03a3855af0a /lib | |
| parent | 91d11da1430b801476f6d5f71ad8669b232731af (diff) | |
| download | e2fsprogs-321649c9f491c2012f5e1a20337fd276bc5290f0.tar.gz | |
mke2fs: recalculate the reserved blocks when the last BG is dropped
mke2fs -m option can set reserved blocks ratio up to 50%. But if the
last block group is not big enough to support the necessary data
structures, it gets dropped, we have to recalculate the number of
reserved blocks so that the reserved blocks matches the requested
percentage.
It also avoids a problem where if the user specifies a reserved blocks
of 50%, and after the last partial block group was dropped, if the
number of reserved blocks is greater than 50%, e2fsck will complain.
Steps to reproduce:
1. Create a FS which has the overhead for the last BG
and specify 50 % for reserved blocks ratio
# mke2fs -m 50 -t ext4 DEV 1025M
mke2fs 1.42.5 (29-Jul-2012)
warning: 256 blocks unused.
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
656640 inodes, 2621440 blocks
1310848 blocks (50.00%) reserved for the super user
~~~~~~~ <-- Reserved blocks exceed 50% of FS blocks count!
2. e2fsck outputs filesystem corruption
# e2fsck DEV
e2fsck 1.42.5 (29-Jul-2012)
Corruption found in superblock. (r_blocks_count = 1310848).
The superblock could not be read or does not describe a correct ext2
filesystem. If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 32768 <device>
Signed-off-by: Akira Fujita <a-fujita@rs.jp.ne.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/ext2fs/initialize.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c index 5a6f8ea2..35677229 100644 --- a/lib/ext2fs/initialize.c +++ b/lib/ext2fs/initialize.c @@ -101,6 +101,7 @@ errcode_t ext2fs_initialize(const char *name, int flags, unsigned reserved_inos; char *buf = 0; char c; + double reserved_ratio; if (!param || !ext2fs_blocks_count(param)) return EXT2_ET_INVALID_ARGUMENT; @@ -391,6 +392,14 @@ ipg_retry: if (rem && (rem < overhead+50)) { ext2fs_blocks_count_set(super, ext2fs_blocks_count(super) - rem); + /* + * If blocks count is changed, we need to recalculate + * reserved blocks count not to exceed 50%. + */ + reserved_ratio = 100.0 * ext2fs_r_blocks_count(param) / + ext2fs_blocks_count(param); + ext2fs_r_blocks_count_set(super, reserved_ratio * + ext2fs_blocks_count(super) / 100.0); goto retry; } |