Re: [PATCH v3] Btrfs-progs: check out if the swap device
On 2013/03/04 1:47, Brendan Hide wrote:
On 2013/02/14 09:53 AM, Tsutomu Itoh wrote:
+if (ret 0) {
+fprintf(stderr, error checking %s status: %s\n, file,
+strerror(-ret));
+exit(1);
+}
...
+/* check if the device is busy */
+fd = open(file, O_RDWR|O_EXCL);
+if (fd 0) {
+fprintf(stderr, unable to open %s: %s\n, file,
+strerror(errno));
+exit(1);
+}
This is fine and works (as tested by David) - but I'm not sure if the below
suggestions from Zach were taken into account.
1. If the check with open(file, O_RDWR|O_EXCL) shows that the device is
available, there's no point in checking if it is mounted as a swap device.
A preliminary check using this could precede all other checks which should
be skipped if it shows success.
2. If there's an error checking the status (for example lets say /proc/swaps
is deprecated), we should print the informational message but not error out.
If open(file, O_RDWR|O_EXCL) failed, we should output an appropriate message
why it failed. So, I'm testing is_swap_device() and check_mounted() first.
But is_swap_device() is not perfect, so I'm trying to open O_EXCL after all
other tests, as a last safety check.
Thanks,
Tsutomu
On 2013/02/13 11:58 AM, Zach Brown wrote:
- First always open with O_EXCL. If it succeeds then there's no reason
to check /proc/swaps at all. (Maybe it doesn't need to try
check_mounted() there either? Not sure if it's protecting against
accidentally mounting mounted shared storage or not.)
...
- At no point is failure of any of the /proc/swaps parsing fatal. It'd
carry on ignoring errors until it doesnt have work to do. It'd only
ever print the nice message when it finds a match.
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Re: [PATCH v3] Btrfs-progs: check out if the swap device
On 2013/02/14 09:53 AM, Tsutomu Itoh wrote:
+ if (ret 0) {
+ fprintf(stderr, error checking %s status: %s\n, file,
+ strerror(-ret));
+ exit(1);
+ }
...
+ /* check if the device is busy */
+ fd = open(file, O_RDWR|O_EXCL);
+ if (fd 0) {
+ fprintf(stderr, unable to open %s: %s\n, file,
+ strerror(errno));
+ exit(1);
+ }
This is fine and works (as tested by David) - but I'm not sure if the
below suggestions from Zach were taken into account.
1. If the check with open(file, O_RDWR|O_EXCL) shows that the device
is available, there's no point in checking if it is mounted as a swap
device. A preliminary check using this could precede all other checks
which should be skipped if it shows success.
2. If there's an error checking the status (for example lets say
/proc/swaps is deprecated), we should print the informational message
but not error out.
On 2013/02/13 11:58 AM, Zach Brown wrote:
- First always open with O_EXCL. If it succeeds then there's no reason
to check /proc/swaps at all. (Maybe it doesn't need to try
check_mounted() there either? Not sure if it's protecting against
accidentally mounting mounted shared storage or not.)
...
- At no point is failure of any of the /proc/swaps parsing fatal. It'd
carry on ignoring errors until it doesnt have work to do. It'd only
ever print the nice message when it finds a match.
--
__
Brendan Hide
http://swiftspirit.co.za/
http://www.webafrica.co.za/?AFF1E97
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Re: [PATCH v3] Btrfs-progs: check out if the swap device
On Thu, Feb 14, 2013 at 04:53:04PM +0900, Tsutomu Itoh wrote: Signed-off-by: Tsutomu Itoh t-i...@jp.fujitsu.com Worked for me here in these situations (ie. mkfs failed, filenames specified given as simple path or with mixture of ./ and ../ leading to the device): * mounted /dev/sdx * /dev/sdx part of a multi-device mounted fs * /dev/sdx swap device * file as a swap device * swap files with funny names: \ \040 \134 \888 space Tested-by: David Sterba dste...@suse.cz -- To unsubscribe from this list: send the line unsubscribe linux-btrfs in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
