[PATCH] btrfs-progs: Add minimum device size check.

[PATCH] btrfs-progs: Add minimum device size check.

[Qu Wenruo]

Btrfs has global block reservation, so even mkfs.btrfs can execute
without problem, there is still a possibility that the filesystem can't
be mounted.
For example when mkfs.btrfs on a 8M file on x86_64 platform, kernel will
refuse to mount due to ENOSPC, since system block group takes 4M and
mixed block group takes 4M, and global block reservation will takes all
the 4M from mixed block group, which makes btrfs unable to create uuid
tree.

This patch will add minimum device size check before actually mkfs.
The minimum size calculation uses a simplified one:
minimum_size_for_each_dev = 2 * (system block group + global block rsv)

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 mkfs.c  | 24 ++++++++++++++++++++++++
 utils.c | 30 ++++++++++++++++++++++++++++++
 utils.h | 13 +++++++++++++
 3 files changed, 67 insertions(+)

diff --git a/mkfs.c b/mkfs.c
index 16e9222..58c751c 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1337,6 +1337,15 @@ int main(int ac, char **av)
 					       "metadata/data groups\n");
 					mixed = 1;
 				}
+				if (block_count < BTRFS_MIN_SIZE_EACH) {
+					fprintf(stderr,
+						"Size '%llu' is too small to make a usable btrfs\n",
+						block_count);
+					fprintf(stderr,
+						"Recommended size for each device is %llu\n",
+						BTRFS_MIN_SIZE_EACH);
+					exit(1);
+				}
 				zero_end = 0;
 				break;
 			case 'V':
@@ -1370,6 +1379,21 @@ int main(int ac, char **av)
 	}
 	while (dev_cnt-- > 0) {
 		file = av[optind++];
+		ret = test_minimum_size(file);
+		if (ret < 0) {
+			fprintf(stderr, "Failed to check size for '%s': %s\n",
+				file, strerror(-ret));
+			exit(1);
+		}
+		if (ret > 0) {
+			fprintf(stderr,
+				"'%s' is too small to make a usable btrfs\n",
+				file);
+			fprintf(stderr,
+				"Recommended size for each device is %llu\n",
+				BTRFS_MIN_SIZE_EACH);
+			exit(1);
+		}
 		if (is_block_device(file))
 			if (test_dev_for_mkfs(file, force_overwrite, estr)) {
 				fprintf(stderr, "Error: %s", estr);
diff --git a/utils.c b/utils.c
index e130849..6f47acc 100644
--- a/utils.c
+++ b/utils.c
@@ -719,6 +719,16 @@ int is_block_device(const char *path)
 	return S_ISBLK(statbuf.st_mode);
 }
 
+int is_regular_file(const char *path)
+{
+	struct stat statbuf;
+
+	if (stat(path, &statbuf) < 0)
+		return -errno;
+
+	return S_ISREG(statbuf.st_mode);
+}
+
 /*
  * check if given path is a mount point
  * return 1 if yes. 0 if no. -1 for error
@@ -2206,3 +2216,23 @@ int find_mount_root(const char *path, char **mount_root)
 	free(longest_match);
 	return ret;
 }
+
+int test_minimum_size(const char *file)
+{
+	int fd;
+	struct stat statbuf;
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+	if (stat(file, &statbuf) < 0) {
+		close(fd);
+		return -errno;
+	}
+	if (btrfs_device_size(fd, &statbuf) < BTRFS_MIN_SIZE_EACH) {
+		close(fd);
+		return 1;
+	}
+	close(fd);
+	return 0;
+}
diff --git a/utils.h b/utils.h
index db8d63c..7f30d12 100644
--- a/utils.h
+++ b/utils.h
@@ -101,5 +101,18 @@ int get_btrfs_mount(const char *dev, char *mp, size_t mp_size);
 int find_mount_root(const char *path, char **mount_root);
 int get_device_info(int fd, u64 devid,
 		struct btrfs_ioctl_dev_info_args *di_args);
+int test_minimum_size(const char *file);
 
+/*
+ * Btrfs minimum size calculation is complicated, it should include at least:
+ * 1. system group size
+ * 2. minimum global block reserve
+ * 3. metadata used at mkfs
+ * 4. space reservation to create uuid for first mount.
+ * Also, raid factor should also be taken into consideration.
+ * To avoid the overkill calculation, (system group + global block rsv) * 2
+ * for *EACH* device should be good enough.
+ */
+#define BTRFS_MIN_SIZE_EACH	(2 * (BTRFS_MKFS_SYSTEM_GROUP_SIZE + \
+				      ((u64)sysconf(_SC_PAGESIZE) << 10)))
 #endif
-- 
2.0.0

Re: [PATCH] btrfs-progs: Add minimum device size check.

[David Sterba]

On Thu, Jun 19, 2014 at 11:25:38AM +0800, Qu Wenruo wrote:
> Btrfs has global block reservation, so even mkfs.btrfs can execute
> without problem, there is still a possibility that the filesystem can't
> be mounted.
> For example when mkfs.btrfs on a 8M file on x86_64 platform, kernel will
> refuse to mount due to ENOSPC, since system block group takes 4M and
> mixed block group takes 4M, and global block reservation will takes all
> the 4M from mixed block group, which makes btrfs unable to create uuid
> tree.
> 
> This patch will add minimum device size check before actually mkfs.
> The minimum size calculation uses a simplified one:
> minimum_size_for_each_dev = 2 * (system block group + global block rsv)

So the global block reserve is set to 1024 * sectorsize. I know the
minimum size guesses are easy to get wrong with various option mixes,
some sane minimum is good. A filesystem in the scale of megabytes is not
recommended anyway.

> --- a/mkfs.c
> +++ b/mkfs.c
> @@ -1337,6 +1337,15 @@ int main(int ac, char **av)
>  					       "metadata/data groups\n");
>  					mixed = 1;
>  				}
> +				if (block_count < BTRFS_MIN_SIZE_EACH) {
> +					fprintf(stderr,
> +						"Size '%llu' is too small to make a usable btrfs\n",
> +						block_count);
> +					fprintf(stderr,
> +						"Recommended size for each device is %llu\n",
> +						BTRFS_MIN_SIZE_EACH);

I'd suggest to merge the messages into one and do not use "Recommended".
As described in the changelog it's the 'minimum' accepted size.

> @@ -1370,6 +1379,21 @@ int main(int ac, char **av)
>  	}
>  	while (dev_cnt-- > 0) {
>  		file = av[optind++];
> +		ret = test_minimum_size(file);
> +		if (ret < 0) {
> +			fprintf(stderr, "Failed to check size for '%s': %s\n",
> +				file, strerror(-ret));
> +			exit(1);
> +		}
> +		if (ret > 0) {
> +			fprintf(stderr,
> +				"'%s' is too small to make a usable btrfs\n",
> +				file);
> +			fprintf(stderr,
> +				"Recommended size for each device is %llu\n",
> +				BTRFS_MIN_SIZE_EACH);
> +			exit(1);

Same here.

> +		}
>  		if (is_block_device(file))
>  			if (test_dev_for_mkfs(file, force_overwrite, estr)) {
>  				fprintf(stderr, "Error: %s", estr);
> --- a/utils.h
> +++ b/utils.h
> @@ -101,5 +101,18 @@ int get_btrfs_mount(const char *dev, char *mp, size_t mp_size);
>  int find_mount_root(const char *path, char **mount_root);
>  int get_device_info(int fd, u64 devid,
>  		struct btrfs_ioctl_dev_info_args *di_args);
> +int test_minimum_size(const char *file);
>  
> +/*
> + * Btrfs minimum size calculation is complicated, it should include at least:
> + * 1. system group size
> + * 2. minimum global block reserve
> + * 3. metadata used at mkfs
> + * 4. space reservation to create uuid for first mount.
> + * Also, raid factor should also be taken into consideration.
> + * To avoid the overkill calculation, (system group + global block rsv) * 2
> + * for *EACH* device should be good enough.
> + */
> +#define BTRFS_MIN_SIZE_EACH	(2 * (BTRFS_MKFS_SYSTEM_GROUP_SIZE + \
> +				      ((u64)sysconf(_SC_PAGESIZE) << 10)))

The use of PAGESIZE here is well hidden in the macro, although it should
be sectorsize of the currently created filesystem. Also,
BTRFS_MIN_SIZE_EACH should be rather denote it's related to a device, so
BTRFS_MIN_DEVICE_SIZE.

Separating the minimum global block reserve size into a macro would be
also cleaner.

Thanks.

Re: [PATCH] btrfs-progs: Add minimum device size check.

[Qu Wenruo]

-------- Original Message --------
Subject: Re: [PATCH] btrfs-progs: Add minimum device size check.
From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2014年06月23日 22:36
> On Thu, Jun 19, 2014 at 11:25:38AM +0800, Qu Wenruo wrote:
>> Btrfs has global block reservation, so even mkfs.btrfs can execute
>> without problem, there is still a possibility that the filesystem can't
>> be mounted.
>> For example when mkfs.btrfs on a 8M file on x86_64 platform, kernel will
>> refuse to mount due to ENOSPC, since system block group takes 4M and
>> mixed block group takes 4M, and global block reservation will takes all
>> the 4M from mixed block group, which makes btrfs unable to create uuid
>> tree.
>>
>> This patch will add minimum device size check before actually mkfs.
>> The minimum size calculation uses a simplified one:
>> minimum_size_for_each_dev = 2 * (system block group + global block rsv)
> So the global block reserve is set to 1024 * sectorsize. I know the
> minimum size guesses are easy to get wrong with various option mixes,
> some sane minimum is good. A filesystem in the scale of megabytes is not
> recommended anyway.
>
>> --- a/mkfs.c
>> +++ b/mkfs.c
>> @@ -1337,6 +1337,15 @@ int main(int ac, char **av)
>>   					       "metadata/data groups\n");
>>   					mixed = 1;
>>   				}
>> +				if (block_count < BTRFS_MIN_SIZE_EACH) {
>> +					fprintf(stderr,
>> +						"Size '%llu' is too small to make a usable btrfs\n",
>> +						block_count);
>> +					fprintf(stderr,
>> +						"Recommended size for each device is %llu\n",
>> +						BTRFS_MIN_SIZE_EACH);
> I'd suggest to merge the messages into one and do not use "Recommended".
> As described in the changelog it's the 'minimum' accepted size.
>
>> @@ -1370,6 +1379,21 @@ int main(int ac, char **av)
>>   	}
>>   	while (dev_cnt-- > 0) {
>>   		file = av[optind++];
>> +		ret = test_minimum_size(file);
>> +		if (ret < 0) {
>> +			fprintf(stderr, "Failed to check size for '%s': %s\n",
>> +				file, strerror(-ret));
>> +			exit(1);
>> +		}
>> +		if (ret > 0) {
>> +			fprintf(stderr,
>> +				"'%s' is too small to make a usable btrfs\n",
>> +				file);
>> +			fprintf(stderr,
>> +				"Recommended size for each device is %llu\n",
>> +				BTRFS_MIN_SIZE_EACH);
>> +			exit(1);
> Same here.
>
>> +		}
>>   		if (is_block_device(file))
>>   			if (test_dev_for_mkfs(file, force_overwrite, estr)) {
>>   				fprintf(stderr, "Error: %s", estr);
>> --- a/utils.h
>> +++ b/utils.h
>> @@ -101,5 +101,18 @@ int get_btrfs_mount(const char *dev, char *mp, size_t mp_size);
>>   int find_mount_root(const char *path, char **mount_root);
>>   int get_device_info(int fd, u64 devid,
>>   		struct btrfs_ioctl_dev_info_args *di_args);
>> +int test_minimum_size(const char *file);
>>   
>> +/*
>> + * Btrfs minimum size calculation is complicated, it should include at least:
>> + * 1. system group size
>> + * 2. minimum global block reserve
>> + * 3. metadata used at mkfs
>> + * 4. space reservation to create uuid for first mount.
>> + * Also, raid factor should also be taken into consideration.
>> + * To avoid the overkill calculation, (system group + global block rsv) * 2
>> + * for *EACH* device should be good enough.
>> + */
>> +#define BTRFS_MIN_SIZE_EACH	(2 * (BTRFS_MKFS_SYSTEM_GROUP_SIZE + \
>> +				      ((u64)sysconf(_SC_PAGESIZE) << 10)))
> The use of PAGESIZE here is well hidden in the macro, although it should
> be sectorsize of the currently created filesystem. Also,
> BTRFS_MIN_SIZE_EACH should be rather denote it's related to a device, so
> BTRFS_MIN_DEVICE_SIZE.
>
> Separating the minimum global block reserve size into a macro would be
> also cleaner.
>
> Thanks.
Thanks for the comment, I'll send the v3 patch fixing all the problem.

Thanks,
Qu

[PATCH] btrfs-progs: Add minimum device size check.

[Qu Wenruo]

Btrfs has global block reservation, so even mkfs.btrfs can execute
without problem, there is still a possibility that the filesystem can't
be mounted.
For example when mkfs.btrfs on a 8M file on x86_64 platform, kernel will
refuse to mount due to ENOSPC, since system block group takes 4M and
mixed block group takes 4M, and global block reservation will takes all
the 4M from mixed block group, which makes btrfs unable to create uuid
tree.

This patch will add minimum device size check before actually mkfs.
The minimum size calculation uses a simplified one:
minimum_size_for_each_dev = 2 * (system block group + global block rsv)

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 mkfs.c  | 24 ++++++++++++++++++++++++
 utils.c | 30 ++++++++++++++++++++++++++++++
 utils.h | 13 +++++++++++++
 3 files changed, 67 insertions(+)

diff --git a/mkfs.c b/mkfs.c
index 16e9222..58c751c 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1337,6 +1337,15 @@ int main(int ac, char **av)
 					       "metadata/data groups\n");
 					mixed = 1;
 				}
+				if (block_count < BTRFS_MIN_SIZE_EACH) {
+					fprintf(stderr,
+						"Size '%llu' is too small to make a usable btrfs\n",
+						block_count);
+					fprintf(stderr,
+						"Recommended size for each device is %llu\n",
+						BTRFS_MIN_SIZE_EACH);
+					exit(1);
+				}
 				zero_end = 0;
 				break;
 			case 'V':
@@ -1370,6 +1379,21 @@ int main(int ac, char **av)
 	}
 	while (dev_cnt-- > 0) {
 		file = av[optind++];
+		ret = test_minimum_size(file);
+		if (ret < 0) {
+			fprintf(stderr, "Failed to check size for '%s': %s\n",
+				file, strerror(-ret));
+			exit(1);
+		}
+		if (ret > 0) {
+			fprintf(stderr,
+				"'%s' is too small to make a usable btrfs\n",
+				file);
+			fprintf(stderr,
+				"Recommended size for each device is %llu\n",
+				BTRFS_MIN_SIZE_EACH);
+			exit(1);
+		}
 		if (is_block_device(file))
 			if (test_dev_for_mkfs(file, force_overwrite, estr)) {
 				fprintf(stderr, "Error: %s", estr);
diff --git a/utils.c b/utils.c
index e130849..6f47acc 100644
--- a/utils.c
+++ b/utils.c
@@ -719,6 +719,16 @@ int is_block_device(const char *path)
 	return S_ISBLK(statbuf.st_mode);
 }
 
+int is_regular_file(const char *path)
+{
+	struct stat statbuf;
+
+	if (stat(path, &statbuf) < 0)
+		return -errno;
+
+	return S_ISREG(statbuf.st_mode);
+}
+
 /*
  * check if given path is a mount point
  * return 1 if yes. 0 if no. -1 for error
@@ -2206,3 +2216,23 @@ int find_mount_root(const char *path, char **mount_root)
 	free(longest_match);
 	return ret;
 }
+
+int test_minimum_size(const char *file)
+{
+	int fd;
+	struct stat statbuf;
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+	if (stat(file, &statbuf) < 0) {
+		close(fd);
+		return -errno;
+	}
+	if (btrfs_device_size(fd, &statbuf) < BTRFS_MIN_SIZE_EACH) {
+		close(fd);
+		return 1;
+	}
+	close(fd);
+	return 0;
+}
diff --git a/utils.h b/utils.h
index db8d63c..7f30d12 100644
--- a/utils.h
+++ b/utils.h
@@ -101,5 +101,18 @@ int get_btrfs_mount(const char *dev, char *mp, size_t mp_size);
 int find_mount_root(const char *path, char **mount_root);
 int get_device_info(int fd, u64 devid,
 		struct btrfs_ioctl_dev_info_args *di_args);
+int test_minimum_size(const char *file);
 
+/*
+ * Btrfs minimum size calculation is complicated, it should include at least:
+ * 1. system group size
+ * 2. minimum global block reserve
+ * 3. metadata used at mkfs
+ * 4. space reservation to create uuid for first mount.
+ * Also, raid factor should also be taken into consideration.
+ * To avoid the overkill calculation, (system group + global block rsv) * 2
+ * for *EACH* device should be good enough.
+ */
+#define BTRFS_MIN_SIZE_EACH	(2 * (BTRFS_MKFS_SYSTEM_GROUP_SIZE + \
+				      ((u64)sysconf(_SC_PAGESIZE) << 10)))
 #endif
-- 
2.0.0