-------- Original Message --------
Subject: Re: [PATCH 4/7] btrfs-progs: Allow parse_qgroupid() to resolve
subvolume path into qgroupid.
From: Wang Shilong <wangshilong1991@xxxxxxxxx>
To: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
Date: 2015年02月27日 16:41
Now parse_qgroupid() can resolve subvolume path into qgroupid.
This is quite handy for handling level 0 qgroupid, and user don't need
to resolve rootid by hand now.
oh, not sure if this is safe, for example, if user do something like:
# btrfs sub create 258(subvolume id = 300)
if 258 is passing, so it will be treated as subvolume id?
Immediate number has higher privilege than path, so 258 is first
considered as a subvolid and path will not be resolved, just as the old
days.
If user really want to do things like that, passing "./258" will be the
best method.
Thanks,
Qu
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
utils.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/utils.c b/utils.c
index fc2791b..509c5ec 100644
--- a/utils.c
+++ b/utils.c
@@ -1708,6 +1708,25 @@ scan_again:
}
/*
+ * Unsafe subvolume check.
+ *
+ * This only checks ino == BTRFS_FIRST_FREE_OBJECTID, even it is not in a
+ * btrfs mount point.
+ * Must use together with other reliable method like btrfs ioctl.
+ */
+static int __is_subvol(char *path)
+{
+ struct stat st;
+ int ret;
+
+ ret = lstat(path, &st);
+ if (ret < 0)
+ return ret;
+
+ return st.st_ino == BTRFS_FIRST_FREE_OBJECTID;
+}
+
+/*
* A not-so-good version fls64. No fascinating optimization since
* no one except parse_size use it
*/
@@ -1802,24 +1821,43 @@ u64 parse_qgroupid(char *p)
char *ptr_parse_end = NULL;
u64 level;
u64 id;
+ int fd;
+ int ret = 0;
+ if (p[0] == '/')
+ goto path;
+
+ /* Numeric format like '0/257' is the primary case */
if (!s) {
id = strtoull(p, &ptr_parse_end, 10);
if (ptr_parse_end != ptr_src_end)
- goto err;
+ goto path;
return id;
}
level = strtoull(p, &ptr_parse_end, 10);
if (ptr_parse_end != s)
- goto err;
+ goto path;
id = strtoull(s+1, &ptr_parse_end, 10);
if (ptr_parse_end != ptr_src_end)
- goto err;
+ goto path;
return (level << BTRFS_QGROUP_LEVEL_SHIFT) | id;
+path:
+ /* Path format like subv at 'my_subvol' is the fallback case */
+ ret = __is_subvol(p);
+ if (ret < 0 || !ret)
+ goto err;
+ fd = open(p, O_RDONLY);
+ if (fd < 0)
+ goto err;
+ ret = lookup_ino_rootid(fd, &id);
+ close(fd);
+ if (ret < 0)
+ goto err;
+ return id;
err:
- fprintf(stderr, "ERROR:invalid qgroupid\n");
+ fprintf(stderr, "ERROR:invalid qgroupid or subvolume path\n");
exit(-1);
}
--
2.3.0
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Best Regards,
Wang Shilong
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