Hi, Eric,
Thanks for your comment.
On 2013/02/12 13:22, Eric Sandeen wrote:
On 2/11/13 7:25 PM, Tsutomu Itoh wrote:
Currently, the following commands succeed.
# cat /proc/swaps
Filename Type Size Used
Priority
/dev/sda3 partition 8388604 0 -1
/dev/sdc8 partition 9765884 0 -2
# mkfs.btrfs /dev/sdc8
WARNING! - Btrfs v0.20-rc1-165-g82ac345 IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
fs created label (null) on /dev/sdc8
nodesize 4096 leafsize 4096 sectorsize 4096 size 9.31GB
Btrfs v0.20-rc1-165-g82ac345
# btrfs fi sh /dev/sdc8
Label: none uuid: fc0bdbd0-7eed-460f-b4e9-131273b66df2
Total devices 1 FS bytes used 28.00KB
devid 1 size 9.31GB used 989.62MB path /dev/sdc8
Btrfs v0.20-rc1-165-g82ac345
#
But we should check out the swap device. So fixed it.
I guess it's nice to parse /proc/swaps to be able to offer the
helpful error message in this case. (though I wonder how long
/proc/swaps will be available, and in this format? Does it count
as ABI?)
Umm, I don't know how long /proc/swaps will be available, too...
Your implementation looks just like the one in e2fsprogs, so it should
work fine.
Yes.
But I also wonder if overall it would be safest to open the device O_EXCL,
which would fail with EBUSY if it were in use for swap, or mounted,
or opened O_EXCL by another process for any other reason:
But details of the error cannot be notified when O_EXCL is used. and,
after is_swap_device(), check_mounted() check state of the mount or not.
So, I chose this one. (read /proc/swaps)
Thanks,
Tsutomu
[root@host tmp]# cat /proc/swaps
Filename Type Size Used Priority
/dev/sda3 partition 2048280 822616 -1
[root@host tmp]# strace -e open ./test
open("/etc/ld.so.cache", O_RDONLY) = 3
open("/lib64/libc.so.6", O_RDONLY) = 3
open("/dev/sda3", O_RDWR|O_EXCL) = -1 EBUSY (Device or resource busy)
open: Device or resource busy
-Eric
Signed-off-by: Tsutomu Itoh <t-i...@jp.fujitsu.com>
---
(this patch is based on Chris's raid56-experimental branch)
---
mkfs.c | 18 ++++++++++++++++++
utils.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
utils.h | 1 +
3 files changed, 68 insertions(+)
diff --git a/mkfs.c b/mkfs.c
index 2d3c2af..fdc3373 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1366,6 +1366,15 @@ int main(int ac, char **av)
if (source_dir == 0) {
file = av[optind++];
+ ret = is_swap_device(file);
+ if (ret < 0) {
+ fprintf(stderr, "error checking %s status\n", file);
+ exit(1);
+ }
+ if (ret == 1) {
+ fprintf(stderr, "%s is a swap device\n", file);
+ exit(1);
+ }
ret = check_mounted(file);
if (ret < 0) {
fprintf(stderr, "error checking %s mount status\n",
file);
@@ -1461,6 +1470,15 @@ int main(int ac, char **av)
int old_mixed = mixed;
file = av[optind++];
+ ret = is_swap_device(file);
+ if (ret < 0) {
+ fprintf(stderr, "error checking %s status\n", file);
+ exit(1);
+ }
+ if (ret == 1) {
+ fprintf(stderr, "%s is a swap device\n", file);
+ exit(1);
+ }
ret = check_mounted(file);
if (ret < 0) {
fprintf(stderr, "error checking %s mount status\n",
diff --git a/utils.c b/utils.c
index f9ee812..0c551a0 100644
--- a/utils.c
+++ b/utils.c
@@ -1386,3 +1386,52 @@ int get_fs_info(int fd, char *path, struct
btrfs_ioctl_fs_info_args *fi_args,
return 0;
}
+
+/*
+ * Checks if the swap device or not.
+ * Returns 1 if the swap device, < 0 on error or 0 if not the swap device.
+ */
+int is_swap_device(const char *file)
+{
+ FILE *f;
+ struct stat st_buf;
+ char buf[1024];
+ char *cp;
+ dev_t rdev;
+ int ret = 0;
+
+ if (stat(file, &st_buf) < 0)
+ return -errno;
+ if (!S_ISBLK(st_buf.st_mode))
+ return 0;
+
+ rdev = st_buf.st_rdev;
+
+ if ((f = fopen("/proc/swaps", "r")) == NULL)
+ return -errno;
+
+ /* skip the first line */
+ if (fgets(buf, sizeof(buf), f) == NULL)
+ goto out;
+
+ while (fgets(buf, sizeof(buf), f) != NULL) {
+ if ((cp = strchr(buf, ' ')) != NULL)
+ *cp = 0;
+ if ((cp = strchr(buf, '\t')) != NULL)
+ *cp = 0;
+ if (strcmp(file, buf) == 0) {
+ ret = 1;
+ break;
+ }
+ if ((stat(buf, &st_buf) == 0) && S_ISBLK(st_buf.st_mode) &&
+ rdev == st_buf.st_rdev) {
+ ret = 1;
+ break;
+ }
+ }
+
+out:
+ fclose(f);
+
+ return ret;
+}
diff --git a/utils.h b/utils.h
index bbcaf6a..60a0fea 100644
--- a/utils.h
+++ b/utils.h
@@ -55,6 +55,7 @@ int get_fs_info(int fd, char *path, struct
btrfs_ioctl_fs_info_args *fi_args,
struct btrfs_ioctl_dev_info_args **di_ret);
char *__strncpy__null(char *dest, const char *src, size_t n);
+int is_swap_device(const char *file);
/* Helper to always get proper size of the destination string */
#define strncpy_null(dest, src) __strncpy__null(dest, src, sizeof(dest))
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