Coda mount has 4 times the specified amount of 1K-blocks
pjcuadra opened this issue · 6 comments
When running df the ouput shows 4xcacheblocks. I tested it with the value specified in /etc/coda/venus.conf and with venus -c <n>. In both cases the same behaviour is seen.
I'm running kernel version 4.15.0-24-generic on Ubuntu 18.04.
Seen in master branch. I'm investigating if it's also present in previous commits/versions.
Yes. What I mean is that if I run venus -c 100000 I'll get a size of 400000 in the coda mount. Bellow the output;
pjcuadra@pjcuadra-vaio:/$ sudo venus -init -c 100000
Date: Sat 07/14/2018
13:58:22 Coda Venus, version 6.14.0
13:58:22 /var/lib/coda/LOG size is 19780620 bytes
13:58:22 /var/lib/coda/DATA size is 79122480 bytes
13:58:22 /var/lib/coda/DATA size is 79122480 bytes
13:58:22 Initializing RVM data...
13:58:22 ...done
13:58:22 Loading RVM data
13:58:22 Starting RealmDB scan
13:58:22 Found 1 realms
13:58:22 starting VDB scan
13:58:22 0 volume replicas
13:58:22 0 replicated volumes
13:58:22 0 CML entries allocated
13:58:22 0 CML entries on free-list
13:58:22 starting FSDB scan (4166, 100000) (25, 75, 4)
13:58:22 0 cache files in table (0 blocks)
13:58:22 4166 cache files on free-list
13:58:23 starting HDB scan
13:58:23 0 hdb entries in table
13:58:23 0 hdb entries on free-list
13:58:23 Kernel version ioctl failed.
13:58:23 Mounting root volume...
13:58:23 Venus starting...
13:58:23 /coda now mounted.
pjcuadra@pjcuadra-vaio:/$ df
Filesystem 1K-blocks Used Available Use% Mounted on
udev 3989196 0 3989196 0% /dev
...
coda 400000 0 375000 0% /coda
What happens is that; in my file system, the block size is in fact 4096. Output below;
pjcuadra@pjcuadra-vaio:/coda$ stat -f .
File: "."
ID: 0 Namelen: 255 Type: coda
Block size: 4096 Fundamental block size: 4096
Blocks: Total: 100000 Free: 100000 Available: 93750
Inodes: Total: 4166 Free: 4163
Aparently, the size of coda's root volume is calculated assuming 1K block size.
You mean something like editing vproc_vfscalls.cc in this way?
#include <sys/statvfs.h>
...
#define CODA_BLOCK_SIZE 1024
...
void vproc::statfs(struct coda_statfs *sfs) {
struct statvfs stat;
LOG(1, ("vproc::statfs\n"));
sfs->f_blocks = CacheBlocks;
sfs->f_bfree = (CacheBlocks - FSDB->DirtyBlockCount());
sfs->f_bavail = FSDB->FreeBlockCount() - FSDB->FreeBlockMargin;
sfs->f_files = CacheFiles;
sfs->f_ffree = FSDB->FreeFsoCount();
/* Get stats from the FS where the cache is stored */
statvfs(CacheDir, &stat);
/* Compensate block size */
sfs->f_blocks *= CODA_BLOCK_SIZE;
sfs->f_blocks /= stat.f_bsize;
sfs->f_bfree *= CODA_BLOCK_SIZE;
sfs->f_bfree /= stat.f_bsize;
sfs->f_bavail *= CODA_BLOCK_SIZE;
sfs->f_bavail /= stat.f_bsize;
}With this change I have the correct output as follows;
pjcuadra@pjcuadra-vaio:/coda$ df
Filesystem 1K-blocks Used Available Use% Mounted on
udev 3989196 0 3989196 0% /dev
...
coda 100000 0 93748 0% /coda
pjcuadra@pjcuadra-vaio:/coda$ stat -f .
File: "."
ID: 0 Namelen: 255 Type: coda
Block size: 4096 Fundamental block size: 4096
Blocks: Total: 25000 Free: 25000 Available: 23437
Inodes: Total: 4166 Free: 4163Shouldn't we maybe make coda kernel "aware" of block size?
You can have a look at the change here pjcuadra/coda/tree/fix/block_size_missmatch
I just checked and the statfs->f_bsize value is not taken from the underlying filesystem block size, it is hardcoded as 4096 in the Linux kernel module. So doing a simple sfs->f_blocks /= 4; probably is good enough.
I just went to check what the FBSD kernel module is doing and discovered that they dropped the Coda kernel module with release 10, either because of how it handled locking or GPL contamination. Either way we don't have to worry about how it used to handle file system block size.