Andreas Dilger wrote:
> Just as an FYI - it probably makes little sense to have a 128MB journal
> for a filesystem you want to use for testing, since it would still write
> 128MB to your loopback device when zeroing the journal. It still makes
> sense for mke2fs and libext2fs to be fixed for correctness, but I think
> it also makes sense for lazy_bg to influence the journal size.
>
yup, it probably should change that heuristic. With lazy_bg, it should probably
look at something like blocks per group * 2 instead of total filesystem blocks...
see below.
>> Unfortunately it also increases mkfs time a bit, as it must search
>> a huge string of unavailable blocks if it has to allocate in the
>> last bg. Ah well...
>>
>
> It also probably makes sense for libext2fs to check group descriptors
> while allocating...
>
yeah... I was going with the "lazy" theme. ;-) (and the
small-functional-change-at-a-time theme...) But for large filesystems, that
would certainly be a bonus.
/*
* Stupid algorithm --- we now just search forward starting from the
* goal. Should put in a smarter one someday....
*/
errcode_t ext2fs_new_block(...
I get the impression that allocation in libext2 is not too glorious in
the first place... :)
-Eric
Anyway, how about something like this for calculating journal size in
the face of lazy_bg. I know the last group may be smaller... but I figure
this is just a heuristic anyway.
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Index: e2fsprogs-1.39_ext4_hg/misc/util.c
===================================================================
--- e2fsprogs-1.39_ext4_hg.orig/misc/util.c
+++ e2fsprogs-1.39_ext4_hg/misc/util.c
@@ -252,8 +252,16 @@ void parse_journal_opts(const char *opts
int figure_journal_size(int size, ext2_filsys fs)
{
blk_t j_blocks;
+ blk_t fs_size;
- if (fs->super->s_blocks_count < 2048) {
+ if (EXT2_HAS_COMPAT_FEATURE(fs->super,
+ EXT2_FEATURE_COMPAT_LAZY_BG)) {
+ fs_size = fs->super->s_blocks_per_group * 2;
+ } else {
+ fs_size = fs->super->s_blocks_count;
+ }
+
+ if (fs_size < 2048) {
fputs(_("\nFilesystem too small for a journal\n"), stderr);
return 0;
}
@@ -276,13 +284,13 @@ int figure_journal_size(int size, ext2_f
return j_blocks;
}
- if (fs->super->s_blocks_count < 32768)
+ if (fs_size < 32768)
j_blocks = 1400;
- else if (fs->super->s_blocks_count < 256*1024)
+ else if (fs_size < 256*1024)
j_blocks = 4096;
- else if (fs->super->s_blocks_count < 512*1024)
+ else if (fs_size < 512*1024)
j_blocks = 8192;
- else if (fs->super->s_blocks_count < 1024*1024)
+ else if (fs_size < 1024*1024)
j_blocks = 16384;
else
j_blocks = 32768;
-
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