Quoting Anand Jain (2013-11-17 21:17:19)
> There is a fix for this (which David has integrated into the branch
> recently). This also needs the kernel side patch which is listed below.
>
> [PATCH v4 1/3] btrfs-progs: mechanism to fetch fsinfo from btrfs-control
> [PATCH v4 2/3] btrfs-progs: fs show should handle if subvol(s) mounted
>
> [PATCH v2] btrfs: add framework to read fs info from btrfs-control
Anand's updated patches are a better way to solve this, but until we get
the kernel feature in, I'm about to commit this patch:
>From 5aff090a3951e7d787b32bb5c49adfec65091385 Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.ma...@fusionio.com>
Date: Mon, 18 Nov 2013 14:18:08 -0500
Subject: [PATCH] btrfs filesystem show: skip duplicate fsids
If a given filesystem is mounted more than once, btrfs fi show will
print dups. This adds a quick and dirty hash table of fsids it
has already printed and makes sure we don't print any fsid more than
once.
Signed-off-by: Chris Mason <chris.ma...@fusionio.com>
---
cmds-filesystem.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 79 insertions(+)
diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index aa361d6..1c1926b 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -38,6 +38,74 @@
#include "commands.h"
#include "list_sort.h"
+
+/*
+ * for btrfs fi show, we maintain a hash of fsids we've already printed.
+ * This way we don't print dups if a given FS is mounted more than once.
+ */
+#define SEEN_FSID_HASH_SIZE 256
+
+struct seen_fsid {
+ u8 fsid[BTRFS_FSID_SIZE];
+ struct seen_fsid *next;
+};
+
+static struct seen_fsid *seen_fsid_hash[SEEN_FSID_HASH_SIZE] = {NULL,};
+
+static int add_seen_fsid(u8 *fsid)
+{
+ u8 hash = fsid[0];
+ int slot = hash % SEEN_FSID_HASH_SIZE;
+ struct seen_fsid *seen = seen_fsid_hash[slot];
+ struct seen_fsid *alloc;
+
+ if (!seen)
+ goto insert;
+
+ while (1) {
+ if (memcmp(seen->fsid, fsid, BTRFS_FSID_SIZE) == 0)
+ return -EEXIST;
+
+ if (!seen->next)
+ break;
+
+ seen = seen->next;
+ }
+
+insert:
+
+ alloc = malloc(sizeof(*alloc));
+ if (!alloc)
+ return -ENOMEM;
+
+ alloc->next = NULL;
+ memcpy(alloc->fsid, fsid, BTRFS_FSID_SIZE);
+
+ if (seen)
+ seen->next = alloc;
+ else
+ seen_fsid_hash[slot] = alloc;
+
+ return 0;
+}
+
+static void free_seen_fsid(void)
+{
+ int slot;
+ struct seen_fsid *seen;
+ struct seen_fsid *next;
+
+ for (slot = 0; slot < SEEN_FSID_HASH_SIZE; slot++) {
+ seen = seen_fsid_hash[slot];
+ while (seen) {
+ next = seen->next;
+ free(seen);
+ seen = next;
+ }
+ seen_fsid_hash[slot] = NULL;
+ }
+}
+
static const char * const filesystem_cmd_group_usage[] = {
"btrfs filesystem [<group>] <command> [<args>]",
NULL
@@ -224,6 +292,9 @@ static void print_one_uuid(struct btrfs_fs_devices
*fs_devices)
u64 devs_found = 0;
u64 total;
+ if (add_seen_fsid(fs_devices->fsid))
+ return;
+
uuid_unparse(fs_devices->fsid, uuidbuf);
device = list_entry(fs_devices->devices.next, struct btrfs_device,
dev_list);
@@ -274,6 +345,13 @@ static int print_one_fs(struct btrfs_ioctl_fs_info_args
*fs_info,
int i;
char uuidbuf[37];
struct btrfs_ioctl_dev_info_args *tmp_dev_info;
+ int ret;
+
+ ret = add_seen_fsid(fs_info->fsid);
+ if (ret == -EEXIST)
+ return 0;
+ else if (ret)
+ return ret;
uuid_unparse(fs_info->fsid, uuidbuf);
printf("Label: %s uuid: %s\n",
@@ -478,6 +556,7 @@ devs_only:
out:
printf("%s\n", BTRFS_BUILD_VERSION);
+ free_seen_fsid();
return 0;
}
--
1.8.2
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