Avoid to scan cdrom and floppy

Hi all,

thanks to the last Hugo's email, I restart to work on the patch which avoid to scan cdrom and floppy during a "btrfs filesystem show" and a "btrfs device scan". Comparing to my previous patch I modified the strategy, and now the scan of the devices is based on the content of the file /proc/partitions. The old behavior may be set passing the "--all-devices" options.

I resend as RFC, because this change may be incompatible with the old behavior. Frankly speaking I don't see any problem, but I think that it is better to discuss in the mailing list.

You can pull the patch also from
http://cassiopea.homelinux.net/git/btrfs-progs-unstable.git
branch
scan-proc-partitions

Comment are welcome

The diff is computed against the Hugo's repository

 btrfs.c        |    4 +-
 btrfs_cmds.c   |   47 ++++++++++++++++++++++++++++++++++++++++----
 man/btrfs.8.in |   26 +++++++++++++++---------
 utils.c        |   58 +++++++++++++++++++++++++++++++++++++++++++++++++
 utils.h        |    2 +
 5 files changed, 120 insertions(+), 17 deletions(-)

index 87cc680..c6ae692 100644
@@ -104,7 +104,7 @@ static struct Command commands[] = {
          NULL
        },
        { do_show_filesystem, 999,
-         "filesystem show", "[<device>|<uuid>|<label>]\n"
+         "filesystem show", "[--all-devices][<uuid>|<label>]\n"
                "Show the info of a btrfs filesystem. If no argument\n"
                "is passed, info of all the btrfs filesystem are shown.",
          NULL

@@ -157,7 +157,7 @@ static struct Command commands[] = {
                "Cancel the balance operation running on <path>."
        },
        { do_scan,
-         999, "device scan", "[<device> [<device>..]\n"
+         999, "device scan", "[--all-devices|<device> [<device>..]\n"
                "Scan all device for or the passed device for a btrfs\n"
                "filesystem.",
          NULL

index 062e7d7..21b1dd5 100644
@@ -590,11 +590,29 @@ int do_fssync(int argc, char **argv)
 int do_scan(int argc, char **argv)
 {
        int     i, fd, e;
-       if(argc<=1){
+       int     checklist = 1;
+       int     devstart = 1;
+
+       if( argc >= 2 && !strcmp(argv[1],"--all-devices")){
+
+               if( argc >2 ){
+                       fprintf(stderr, "ERROR: too may arguments\n");
+                        return 22;
+                }
+
+               checklist = 0;
+               devstart += 1;
+       }
+
+       if(argc<=devstart){
+
                int ret;
 
                printf("Scanning for Btrfs filesystems\n");

ghigo@venice:~/btrfs/btrfs-progs-unstable$ git diff integration-hugo-mills | cat

index 87cc680..c6ae692 100644
@@ -104,7 +104,7 @@ static struct Command commands[] = {
          NULL
        },
        { do_show_filesystem, 999,
-         "filesystem show", "[<device>|<uuid>|<label>]\n"
+         "filesystem show", "[--all-devices][<uuid>|<label>]\n"
                "Show the info of a btrfs filesystem. If no argument\n"
                "is passed, info of all the btrfs filesystem are shown.",
          NULL

@@ -157,7 +157,7 @@ static struct Command commands[] = {
                "Cancel the balance operation running on <path>."
        },
        { do_scan,
-         999, "device scan", "[<device> [<device>..]\n"
+         999, "device scan", "[--all-devices|<device> [<device>..]\n"
                "Scan all device for or the passed device for a btrfs\n"
                "filesystem.",
          NULL

index 062e7d7..21b1dd5 100644
@@ -590,11 +590,29 @@ int do_fssync(int argc, char **argv)
 int do_scan(int argc, char **argv)
 {
        int     i, fd, e;
-       if(argc<=1){
+       int     checklist = 1;
+       int     devstart = 1;
+
+       if( argc >= 2 && !strcmp(argv[1],"--all-devices")){
+
+               if( argc >2 ){
+                       fprintf(stderr, "ERROR: too may arguments\n");
+                        return 22;
+                }
+
+               checklist = 0;
+               devstart += 1;
+       }
+
+       if(argc<=devstart){
+
                int ret;
 
                printf("Scanning for Btrfs filesystems\n");
-               ret = btrfs_scan_one_dir("/dev", 1);
+               if(checklist)
+                       ret = btrfs_scan_block_devices(1);
+               else
+                       ret = btrfs_scan_one_dir("/dev", 1);
                if (ret){
                        fprintf(stderr, "ERROR: error %d while 

scanning\n", ret);
                        return 18;
@@ -608,7 +626,7 @@ int do_scan(int argc, char **argv)
                return 10;
        }

- for( i = 1 ; i < argc ; i++ ){

+       for( i = devstart ; i < argc ; i++ ){
                struct btrfs_ioctl_vol_args args;
                int ret;

@@ -731,14 +749,33 @@ int do_show_filesystem(int argc, char **argv)

        struct list_head *all_uuids;
        struct btrfs_fs_devices *fs_devices;
        struct list_head *cur_uuid;
-       char *search = argv[1];
+       char *search = 0;
        int ret;

+ int checklist = 1;
+ int searchstart = 1;
+
+ if( argc >= 2 && !strcmp(argv[1],"--all-devices")){
+ checklist = 0;
+ searchstart += 1;
+ }
+
+ if( argc > searchstart+1 ){
+ fprintf(stderr, "ERROR: too many arguments\n");
+ return 22;
+ }
+
+ if(checklist)
+ ret = btrfs_scan_block_devices(0);
+ else
+ ret = btrfs_scan_one_dir("/dev", 0);

-       ret = btrfs_scan_one_dir("/dev", 0);
        if (ret){
                fprintf(stderr, "ERROR: error %d while scanning\n", ret);
                return 18;
        }

+
+ if(searchstart < argc)
+ search = argv[searchstart];

        all_uuids = btrfs_scanned_uuids();
        list_for_each(cur_uuid, all_uuids) {

index cd436f9..91663e5 100644
@@ -22,6 +22,7 @@ btrfs \- control a btrfs filesystem
 \fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
 .PP
 \fBbtrfs\fP \fBfilesystem defrag\fP\fI [options] <file>|<dir> 

[<file>|<dir>...]\fP
+.PP
\fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <last_gen>\fP
.PP
\fBbtrfs\fP \fBfilesystem balance\fP [\fB-wcv\fP] [\fB--wait\fP]
[\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP @@ -34,9 +35,9 @@ btrfs \- control a btrfs filesystem
.PP
\fBbtrfs\fP \fBfilesystem defragment\fP\fI <file>|<dir>
[<file>|<dir>...]\fP
.PP
-\fBbtrfs\fP \fBdevice scan\fP\fI [<device>...]\fP
+\fBbtrfs\fP \fBdevice scan\fP\fI [--all-devices|<device> [<device>...]]\fP
.PP
-\fBbtrfs\fP \fBdevice show\fP\fI [<device>|<uuid>|<label>]\fP
+\fBbtrfs\fP \fBdevice show\fP\fI [--all-devices|<uuid>|<label>]\fP
.PP
\fBbtrfs\fP \fBdevice add\fP\fI <device> [<device>...] <path> \fP
.PP
@@ -148,11 +149,6 @@ use it if you use snapshots, have de-duplicated your data or made copies with
List the recently modified files in a subvolume, after
\fI<last_gen>\fR ID.
.TP

-\fBdevice scan\fR \fI[<device>...]\fR
-Scan devices for a btrfs filesystem. If no devices are passed, \fBbtrfs\fR scans -all the block devices.
-.TP
-
\fBfilesystem sync\fR\fI <path> \fR
Force a sync for the filesystem identified by \fI<path>\fR.
.TP
@@ -197,9 +193,11 @@ NOTE: Currently there are the following limitations:
- the filesystem should not have more than one device.
.TP

-\fBfilesystem show\fR [<uuid>|<label>]\fR
-Show the btrfs filesystem with some additional info. If no UUID or label is -passed, \fBbtrfs\fR show info of all the btrfs filesystem. +\fBfilesystem show\fR [--all-devices|<uuid>|<label>]\fR
+Show the btrfs filesystem with some additional info. If no \fIUUID\fP or +\fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem. +If \fB--all-devices\fP is passed, all the devices under /dev are scanned; +otherwise the devices list is extracted from the /proc/partitions file.
.TP

\fBdevice balance\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP]
[\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP @@ -224,6 +222,14 @@ Add device(s) to the filesystem identified by \fI<path>\fR.
Remove device(s) from a filesystem identified by \fI<path>\fR.
.TP

+\fBdevice scan\fR \fI[--all-devices|<device> [<device>...]\fR +If one or more devices are passed, these are scanned for a btrfs filesystem. +If no devices are passed, \fBbtrfs\fR scans all the block devices listed +in the /proc/partitions file.
+Finally, if \fB--all-devices\fP is passed, all the devices under /dev are +scanned.
+.TP
+
\fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
Start a scrub on all devices of the filesystem identified by
\fI<path>\fR or on
a single \fI<device>\fR. Without options, scrub is started as a background

index 167021a..0d7ba43 100644
@@ -44,4 +44,6 @@ int btrfs_device_already_in_root(struct btrfs_root *root, int fd,
 char *pretty_sizes(u64 size);
 int check_label(char *input);
 int get_mountpt(char *dev, char *mntpt, size_t size);
+
+int btrfs_scan_block_devices(int run_ioctl);
 #endif

Hallo, Goffredo,

Du meintest am 15.06.11:

Thank you - it's nice for all who don't use udev.

Viele Gruesse!
Helmut

Who the hell doesn't use udev?

Josef

Hallo, Josef,

Du meintest am 16.06.11:

Me - p.e.
"udev" may be interesting for desktop users, for multimedia computers. It's not necessary for a simple server, for a machine where the administrator wants to rule instead of "udev".

If the developers of "btrfs" really do mean that "udev" has to run on the machine which uses "btrfs" then they have to say so, and they have to check wether this (possible) condition is redeemed.

Not only in the "devices" environment.

Viele Gruesse!
Helmut

You don't need udev to use btrfs, I've just not seen a distro that allows you to not run with udev, so my question is more curiosity than anything. Thanks,

Josef

Hallo, Josef,

Du meintest am 16.06.11:

But the developers seem to use only machines where "udev" runs.

p.e. when testing the disks (I've told this bug about 1 year ago), p.e. with "/dev/btrfs-control".

"btrfs-control" has to exist before btrfs is started, and there is neither a hint in the documentation nor a check.

Viele Gruesse!
Helmut

Hi Helmut

Sorry Helmut, but I don't understand if you are blaming about lack of documentation or about a problem.

The fact that the file /dev/btrfs-control doesn't exist, is not a bug/problem of btrfs. This file should be created by the distribution: or via the udev or via devtmpfs or statically. In this is not different by any other device (like /dev/sdaX for example). They have to exists before mounting the root-filesystem.

BR
G.Baroncelli