[RFC] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[RFC] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[Goffredo Baroncelli]

Hi,

this is a repost of an old patch (~2017). At the time it din't received
any feedback. I repost it hoping that it still be interested.

This patch set is the btrfs-prog related one; another one related to the
kernel is send separately.

This patch set createa a new ioctl BTRFS_IOC_GET_CHUNK_INFO.
The aim is to replace the BTRFS_IOC_TREE_SEARCH ioctl
used by "btrfs fi usage" to obtain information about the 
chunks/block groups. 

The problems in using the BTRFS_IOC_TREE_SEARCH is that it access
the very low data structure of BTRFS. This means: 
1) this would be complicated a possible change of the disk format
2) it requires the root privileges

The BTRFS_IOC_GET_CHUNK_INFO ioctl can be called even from a not root
user: I think that the data exposed are not sensibile data.

These patches allow to use "btrfs fi usage" without root privileges.

before:
-------------------------------------------

$ btrfs fi us /
WARNING: cannot read detailed chunk info, per-device usage will not be shown, run as root
Overall:
    Device size:		 100.00GiB
    Device allocated:		  26.03GiB
    Device unallocated:		  73.97GiB
    Device missing:		     0.00B
    Used:			  17.12GiB
    Free (estimated):		  80.42GiB	(min: 80.42GiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		  53.12MiB	(used: 0.00B)

Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)

Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)

System,single: Size:32.00MiB, Used:16.00KiB (0.05%)

after:
-----------------------------------------------
$ ./btrfs fi us /
Overall:
    Device size:		 100.00GiB
    Device allocated:		  26.03GiB
    Device unallocated:		  73.97GiB
    Device missing:		     0.00B
    Used:			  17.12GiB
    Free (estimated):		  80.42GiB	(min: 80.42GiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		  53.12MiB	(used: 0.00B)

Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
   /dev/sdd3	  23.00GiB

Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
   /dev/sdd3	   3.00GiB

System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
   /dev/sdd3	  32.00MiB

Unallocated:
   /dev/sdd3	  73.97GiB

Comments are welcome
BR
G.Baroncelli


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

[PATCH 1/3] btrfs-progs: remove use BLKGETSIZE64

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

Allow the get_partition_size() to be called without
root privileges.

Signed-off-by: Goffredo baroncelli <kreijack@inwind.it>
---
 common/device-utils.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/common/device-utils.c b/common/device-utils.c
index b03d62fa..9519dbce 100644
--- a/common/device-utils.c
+++ b/common/device-utils.c
@@ -17,6 +17,8 @@
 #include <sys/ioctl.h>
 #include <sys/mount.h>
 #include <sys/statfs.h>
+#include <sys/types.h>
+#include <sys/sysmacros.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -238,17 +240,28 @@ u64 disk_size(const char *path)
 
 u64 get_partition_size(const char *dev)
 {
-	u64 result;
-	int fd = open(dev, O_RDONLY);
+	struct stat statbuf;
+	int r;
+	int fd;
+	char buf[100];
 
-	if (fd < 0)
+	r = stat(dev, &statbuf);
+	if (r != 0)
 		return 0;
-	if (ioctl(fd, BLKGETSIZE64, &result) < 0) {
-		close(fd);
-		return 0;
-	}
+
+	snprintf(buf, sizeof(buf),
+		"/sys/dev/block/%d:%d/size", gnu_dev_major(statbuf.st_rdev),
+		 gnu_dev_minor(statbuf.st_rdev));
+
+	fd = open(buf, O_RDONLY);
+	BUG_ON(fd < 0);
+
+	r = read(fd, buf, sizeof(buf)-1);
 	close(fd);
 
-	return result;
+	BUG_ON(r < 0);
+	buf[r] = 0;
+
+	return atoll(buf) * 512;
 }
 
-- 
2.25.1

[PATCH 2/3] btrfs-progs: Add BTRFS_IOC_GET_CHUNK_INFO ioctl.

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
---
 ioctl.h | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/ioctl.h b/ioctl.h
index 4e7efd94..bdf70849 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -775,6 +775,64 @@ struct btrfs_ioctl_get_subvol_rootref_args {
 };
 BUILD_ASSERT(sizeof(struct btrfs_ioctl_get_subvol_rootref_args) == 4096);
 
+struct btrfs_chunk_info_stripe {
+	__u64 devid;
+	__u64 offset;
+	__u8 dev_uuid[BTRFS_UUID_SIZE];
+};
+
+struct btrfs_chunk_info {
+	/* logical start of this chunk */
+	__u64 offset;
+	/* size of this chunk in bytes */
+	__u64 length;
+
+	__u64 stripe_len;
+	__u64 type;
+
+	/* 2^16 stripes is quite a lot, a second limit is the size of a single
+	 * item in the btree
+	 */
+	__u16 num_stripes;
+
+	/* sub stripes only matter for raid10 */
+	__u16 sub_stripes;
+
+	struct btrfs_chunk_info_stripe stripes[1];
+	/* additional stripes go here */
+};
+
+struct btrfs_ioctl_chunk_info {
+	/* offset to start the search; after the ioctl, this field contains
+	 * the next offset to start a search
+	 */
+	u64			offset;		/* in/out */
+	/* size of the passed buffer, including btrfs_ioctl_chunk_info */
+	u32			buf_size;	/* in     */
+	/*  number of items returned */
+	u32			items_count;	/* out    */
+};
+
+static inline struct btrfs_chunk_info *
+btrfs_first_chunk_info(struct btrfs_ioctl_chunk_info *bici)
+{
+	return (struct btrfs_chunk_info *)((char *)bici +
+		sizeof(struct btrfs_ioctl_chunk_info));
+}
+
+static inline int btrfs_chunk_info_size(struct btrfs_chunk_info *ci)
+{
+	return sizeof(struct btrfs_chunk_info) +
+		sizeof(struct btrfs_chunk_info_stripe) * (ci->num_stripes-1);
+}
+
+static inline struct btrfs_chunk_info *
+btrfs_next_chunk_info(struct btrfs_chunk_info *ci)
+{
+	return (struct btrfs_chunk_info *)((char *)ci +
+		btrfs_chunk_info_size(ci));
+}
+
 /* Error codes as returned by the kernel */
 enum btrfs_err_code {
 	notused,
@@ -945,6 +1003,8 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
 				struct btrfs_ioctl_ino_lookup_user_args)
 #define BTRFS_IOC_SNAP_DESTROY_V2 _IOW(BTRFS_IOCTL_MAGIC, 63, \
 				   struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_GET_CHUNK_INFO _IOR(BTRFS_IOCTL_MAGIC, 64, \
+				   struct btrfs_ioctl_chunk_info)
 
 #ifdef __cplusplus
 }
-- 
2.25.1

[PATCH 3/3] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack@inwind.it>

Use the new ioctl BTRFS_IOC_GET_CHUNK_INFO in load_chunk_info() instead of
the BTRFS_IOC_TREE_SEARCH. The old method is still present as fallback for
compatibility reason.

The goal is to avoid BTRFS_IOC_TREE_SEARCH because it requires root
privileges.

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
---
 cmds/filesystem-usage.c | 108 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 105 insertions(+), 3 deletions(-)

diff --git a/cmds/filesystem-usage.c b/cmds/filesystem-usage.c
index aa7065d5..79792ee1 100644
--- a/cmds/filesystem-usage.c
+++ b/cmds/filesystem-usage.c
@@ -39,7 +39,7 @@
 /*
  * Add the chunk info to the chunk_info list
  */
-static int add_info_to_list(struct chunk_info **info_ptr,
+static int legacy_add_info_to_list(struct chunk_info **info_ptr,
 			int *info_count,
 			struct btrfs_chunk *chunk)
 {
@@ -130,7 +130,8 @@ static int cmp_chunk_info(const void *a, const void *b)
 		((struct chunk_info *)b)->type);
 }
 
-static int load_chunk_info(int fd, struct chunk_info **info_ptr, int *info_count)
+static int legacy_load_chunk_info(int fd, struct chunk_info **info_ptr,
+					int *info_count)
 {
 	int ret;
 	struct btrfs_ioctl_search_args args;
@@ -182,7 +183,7 @@ static int load_chunk_info(int fd, struct chunk_info **info_ptr, int *info_count
 			off += sizeof(*sh);
 			item = (struct btrfs_chunk *)(args.buf + off);
 
-			ret = add_info_to_list(info_ptr, info_count, item);
+			ret = legacy_add_info_to_list(info_ptr, info_count, item);
 			if (ret) {
 				*info_ptr = NULL;
 				return 1;
@@ -215,6 +216,107 @@ static int load_chunk_info(int fd, struct chunk_info **info_ptr, int *info_count
 	return 0;
 }
 
+/*
+ * Add the chunk info to the chunk_info list
+ */
+static int add_info_to_list(struct chunk_info **info_ptr,
+			int *info_count,
+			struct btrfs_chunk_info *chunk)
+{
+
+	u64 type = chunk->type;
+	u64 size = chunk->length;
+	int num_stripes = chunk->num_stripes;
+	int j;
+
+	for (j = 0 ; j < num_stripes ; j++) {
+		int i;
+		struct chunk_info *p = NULL;
+		u64    devid;
+
+		devid = chunk->stripes[j].devid;
+
+		for (i = 0 ; i < *info_count ; i++)
+			if ((*info_ptr)[i].type == type &&
+			    (*info_ptr)[i].devid == devid &&
+			    (*info_ptr)[i].num_stripes == num_stripes) {
+				p = (*info_ptr) + i;
+				break;
+			}
+
+		if (!p) {
+			int tmp = sizeof(struct btrfs_chunk) *
+						(*info_count + 1);
+			struct chunk_info *res = realloc(*info_ptr, tmp);
+
+			if (!res) {
+				free(*info_ptr);
+				error("not enough memory");
+				return -ENOMEM;
+			}
+
+			*info_ptr = res;
+			p = res + *info_count;
+			(*info_count)++;
+
+			p->devid = devid;
+			p->type = type;
+			p->size = 0;
+			p->num_stripes = num_stripes;
+		}
+
+		p->size += size;
+
+	}
+
+	return 0;
+
+}
+
+static int load_chunk_info(int fd, struct chunk_info **info_ptr,
+				int *info_count)
+{
+
+	char buf[4096];
+	struct btrfs_ioctl_chunk_info *bici =
+		(struct btrfs_ioctl_chunk_info *)buf;
+	int cont;
+
+	bici->buf_size = sizeof(buf);
+	bici->offset = (u64)0;
+
+	do {
+		int i;
+		struct btrfs_chunk_info *ci;
+		int ret;
+
+		cont = false;
+		ret = ioctl(fd, BTRFS_IOC_GET_CHUNK_INFO, bici);
+		if (ret < 0) {
+			int e = errno;
+
+			if (e == ENOTTY)
+				return legacy_load_chunk_info(fd, info_ptr,
+								info_count);
+			else if (e == EAGAIN)
+				cont = true;
+			else
+				return -e;
+		}
+
+		ci = btrfs_first_chunk_info(bici);
+		for (i = 0 ; i < bici->items_count ; i++) {
+			add_info_to_list(info_ptr, info_count, ci);
+			ci = btrfs_next_chunk_info(ci);
+		}
+
+	} while (cont);
+
+	qsort(*info_ptr, *info_count, sizeof(struct chunk_info),
+		cmp_chunk_info);
+
+	return 0;
+}
 /*
  * Helper to sort the struct btrfs_ioctl_space_info
  */
-- 
2.25.1

Re: [RFC] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[Goffredo Baroncelli]

PING,

does someone find interest on this kind of patch ?

BR
G.Baroncelli

On 3/15/20 4:24 PM, Goffredo Baroncelli wrote:
> 
> Hi,
> 
> this is a repost of an old patch (~2017). At the time it din't received
> any feedback. I repost it hoping that it still be interested.
> 
> This patch set is the btrfs-prog related one; another one related to the
> kernel is send separately.
> 
> This patch set createa a new ioctl BTRFS_IOC_GET_CHUNK_INFO.
> The aim is to replace the BTRFS_IOC_TREE_SEARCH ioctl
> used by "btrfs fi usage" to obtain information about the
> chunks/block groups.
> 
> The problems in using the BTRFS_IOC_TREE_SEARCH is that it access
> the very low data structure of BTRFS. This means:
> 1) this would be complicated a possible change of the disk format
> 2) it requires the root privileges
> 
> The BTRFS_IOC_GET_CHUNK_INFO ioctl can be called even from a not root
> user: I think that the data exposed are not sensibile data.
> 
> These patches allow to use "btrfs fi usage" without root privileges.
> 
> before:
> -------------------------------------------
> 
> $ btrfs fi us /
> WARNING: cannot read detailed chunk info, per-device usage will not be shown, run as root
> Overall:
>      Device size:		 100.00GiB
>      Device allocated:		  26.03GiB
>      Device unallocated:		  73.97GiB
>      Device missing:		     0.00B
>      Used:			  17.12GiB
>      Free (estimated):		  80.42GiB	(min: 80.42GiB)
>      Data ratio:			      1.00
>      Metadata ratio:		      1.00
>      Global reserve:		  53.12MiB	(used: 0.00B)
> 
> Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
> 
> Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
> 
> System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
> 
> after:
> -----------------------------------------------
> $ ./btrfs fi us /
> Overall:
>      Device size:		 100.00GiB
>      Device allocated:		  26.03GiB
>      Device unallocated:		  73.97GiB
>      Device missing:		     0.00B
>      Used:			  17.12GiB
>      Free (estimated):		  80.42GiB	(min: 80.42GiB)
>      Data ratio:			      1.00
>      Metadata ratio:		      1.00
>      Global reserve:		  53.12MiB	(used: 0.00B)
> 
> Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
>     /dev/sdd3	  23.00GiB
> 
> Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
>     /dev/sdd3	   3.00GiB
> 
> System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
>     /dev/sdd3	  32.00MiB
> 
> Unallocated:
>     /dev/sdd3	  73.97GiB
> 
> Comments are welcome
> BR
> G.Baroncelli
> 
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

Re: [RFC] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[Goffredo Baroncelli]

Gentle ping.

BR
G.Baroncelli

On 3/15/20 4:24 PM, Goffredo Baroncelli wrote:> > Hi,> 
> this is a repost of an old patch (~2017). At the time it din't received
> any feedback. I repost it hoping that it still be interested.
> 
> This patch set is the btrfs-prog related one; another one related to the
> kernel is send separately.
> 
> This patch set createa a new ioctl BTRFS_IOC_GET_CHUNK_INFO.
> The aim is to replace the BTRFS_IOC_TREE_SEARCH ioctl
> used by "btrfs fi usage" to obtain information about the
> chunks/block groups.
> 
> The problems in using the BTRFS_IOC_TREE_SEARCH is that it access
> the very low data structure of BTRFS. This means:
> 1) this would be complicated a possible change of the disk format
> 2) it requires the root privileges
> 
> The BTRFS_IOC_GET_CHUNK_INFO ioctl can be called even from a not root
> user: I think that the data exposed are not sensibile data.
> 
> These patches allow to use "btrfs fi usage" without root privileges.
> 
> before:
> -------------------------------------------
> 
> $ btrfs fi us /
> WARNING: cannot read detailed chunk info, per-device usage will not be shown, run as root
> Overall:
>      Device size:		 100.00GiB
>      Device allocated:		  26.03GiB
>      Device unallocated:		  73.97GiB
>      Device missing:		     0.00B
>      Used:			  17.12GiB
>      Free (estimated):		  80.42GiB	(min: 80.42GiB)
>      Data ratio:			      1.00
>      Metadata ratio:		      1.00
>      Global reserve:		  53.12MiB	(used: 0.00B)
> 
> Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
> 
> Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
> 
> System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
> 
> after:
> -----------------------------------------------
> $ ./btrfs fi us /
> Overall:
>      Device size:		 100.00GiB
>      Device allocated:		  26.03GiB
>      Device unallocated:		  73.97GiB
>      Device missing:		     0.00B
>      Used:			  17.12GiB
>      Free (estimated):		  80.42GiB	(min: 80.42GiB)
>      Data ratio:			      1.00
>      Metadata ratio:		      1.00
>      Global reserve:		  53.12MiB	(used: 0.00B)
> 
> Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
>     /dev/sdd3	  23.00GiB
> 
> Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
>     /dev/sdd3	   3.00GiB
> 
> System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
>     /dev/sdd3	  32.00MiB
> 
> Unallocated:
>     /dev/sdd3	  73.97GiB
> 
> Comments are welcome
> BR
> G.Baroncelli
> 
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

Re: [RFC] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[Goffredo Baroncelli]

Gentle ping.

BR
G.Baroncelli
On 3/15/20 4:24 PM, Goffredo Baroncelli wrote:
> 
> Hi,
> 
> this is a repost of an old patch (~2017). At the time it din't received
> any feedback. I repost it hoping that it still be interested.
> 
> This patch set is the btrfs-prog related one; another one related to the
> kernel is send separately.
> 
> This patch set createa a new ioctl BTRFS_IOC_GET_CHUNK_INFO.
> The aim is to replace the BTRFS_IOC_TREE_SEARCH ioctl
> used by "btrfs fi usage" to obtain information about the
> chunks/block groups.
> 
> The problems in using the BTRFS_IOC_TREE_SEARCH is that it access
> the very low data structure of BTRFS. This means:
> 1) this would be complicated a possible change of the disk format
> 2) it requires the root privileges
> 
> The BTRFS_IOC_GET_CHUNK_INFO ioctl can be called even from a not root
> user: I think that the data exposed are not sensibile data.
> 
> These patches allow to use "btrfs fi usage" without root privileges.
> 
> before:
> -------------------------------------------
> 
> $ btrfs fi us /
> WARNING: cannot read detailed chunk info, per-device usage will not be shown, run as root
> Overall:
>      Device size:		 100.00GiB
>      Device allocated:		  26.03GiB
>      Device unallocated:		  73.97GiB
>      Device missing:		     0.00B
>      Used:			  17.12GiB
>      Free (estimated):		  80.42GiB	(min: 80.42GiB)
>      Data ratio:			      1.00
>      Metadata ratio:		      1.00
>      Global reserve:		  53.12MiB	(used: 0.00B)
> 
> Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
> 
> Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
> 
> System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
> 
> after:
> -----------------------------------------------
> $ ./btrfs fi us /
> Overall:
>      Device size:		 100.00GiB
>      Device allocated:		  26.03GiB
>      Device unallocated:		  73.97GiB
>      Device missing:		     0.00B
>      Used:			  17.12GiB
>      Free (estimated):		  80.42GiB	(min: 80.42GiB)
>      Data ratio:			      1.00
>      Metadata ratio:		      1.00
>      Global reserve:		  53.12MiB	(used: 0.00B)
> 
> Data,single: Size:23.00GiB, Used:16.54GiB (71.93%)
>     /dev/sdd3	  23.00GiB
> 
> Metadata,single: Size:3.00GiB, Used:588.94MiB (19.17%)
>     /dev/sdd3	   3.00GiB
> 
> System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
>     /dev/sdd3	  32.00MiB
> 
> Unallocated:
>     /dev/sdd3	  73.97GiB
> 
> Comments are welcome
> BR
> G.Baroncelli
> 
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

[RFC] btrfs-progs: use the new ioctl BTRFS_IOC_GET_CHUNK_INFO

[Goffredo Baroncelli]

Hi all,

this patches set uses the new ioctl BTRFS_IOC_GET_CHUNK_INFO to get
information about the chunk (see my other emails). 

The first patch change the function get_partition_size() to avoid
ioctl which would require root privileges (BLKGETSIZE64).
Instead it obtain the information via the sysfs filesystem.

The second patch use the BTRFS_IOC_GET_CHUNK_INFO instead of
TREE_SEARCH_IOCTL. The old code is still in place as fallback
when the kernel doesn't have the new ioctl.

These patches allow to use "btrfs fi usage" without root privileges.

Comments are welcome
BR
G.Baroncelli

--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5