[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