[2/3,RESEND,Rebased] btrfs: add readmirror property framework
diff mbox series

Message ID 20190626083402.1895-3-anand.jain@oracle.com
State New
Headers show
Series
  • readmirror feature
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Commit Message

Anand Jain June 26, 2019, 8:34 a.m. UTC
Function call chain  __btrfs_map_block()->find_live_mirror() uses
thread %pid to determine the %mirror_num for the read when mirror_num=0
in the argument.

This patch introduces a framework so that readmirror is a configurable
parameter, with default set to pid.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/props.c   | 41 +++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.c |  9 ++++++++-
 fs/btrfs/volumes.h |  6 ++++++
 3 files changed, 55 insertions(+), 1 deletion(-)

Comments

David Sterba July 23, 2019, 2:57 p.m. UTC | #1
On Wed, Jun 26, 2019 at 04:34:01PM +0800, Anand Jain wrote:
> Function call chain  __btrfs_map_block()->find_live_mirror() uses
> thread %pid to determine the %mirror_num for the read when mirror_num=0
> in the argument.
> 
> This patch introduces a framework so that readmirror is a configurable
> parameter, with default set to pid.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/props.c   | 41 +++++++++++++++++++++++++++++++++++++++++
>  fs/btrfs/volumes.c |  9 ++++++++-
>  fs/btrfs/volumes.h |  6 ++++++
>  3 files changed, 55 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
> index f9143f7c006d..0dc26a154a98 100644
> --- a/fs/btrfs/props.c
> +++ b/fs/btrfs/props.c
> @@ -10,6 +10,7 @@
>  #include "ctree.h"
>  #include "xattr.h"
>  #include "compression.h"
> +#include "volumes.h"
>  
>  #define BTRFS_PROP_HANDLERS_HT_BITS 8
>  static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
> @@ -312,6 +313,39 @@ static const char *prop_compression_extract(struct inode *inode)
>  	return NULL;
>  }
>  
> +static int prop_readmirror_validate(struct inode *inode, const char *value,
> +				    size_t len)
> +{
> +	struct btrfs_root *root = BTRFS_I(inode)->root;
> +
> +	if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID)
> +		return -EINVAL;
> +
> +	if (!len)
> +		return 0;
> +
> +	return -EINVAL;
> +}
> +
> +static int prop_readmirror_apply(struct inode *inode, const char *value,
> +				 size_t len)
> +{
> +	struct btrfs_fs_devices *fs_devices = btrfs_sb(inode->i_sb)->fs_devices;
> +
> +	fs_devices->readmirror_policy = BTRFS_READMIRROR_DEFAULT;
> +
> +	return 0;
> +}
> +
> +static const char *prop_readmirror_extract(struct inode *inode)
> +{
> +	/*
> +	 * readmirror policy is applied for the whole FS, inheritance is not
> +	 * applicable.
> +	 */

Extract is the 'get' implementation of the property, not inheritance, or
I don't understand what does the comment refer to.

> +	return NULL;

The return value should reflect the status of the property, ie.
basically the same value that would set the current state.

> +}
> +
>  static struct prop_handler prop_handlers[] = {
>  	{
>  		.xattr_name = XATTR_BTRFS_PREFIX "compression",
> @@ -320,6 +354,13 @@ static struct prop_handler prop_handlers[] = {
>  		.extract = prop_compression_extract,
>  		.inheritable = 1
>  	},
> +	{
> +		.xattr_name = XATTR_BTRFS_PREFIX "readmirror",
> +		.validate = prop_readmirror_validate,
> +		.apply = prop_readmirror_apply,
> +		.extract = prop_readmirror_extract,
> +		.inheritable = 0
> +	},
>  };
>  
>  static int inherit_props(struct btrfs_trans_handle *trans,
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index a13ddba1ebc3..d72850ed4f88 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -5490,7 +5490,14 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info,
>  	else
>  		num_stripes = map->num_stripes;
>  
> -	preferred_mirror = first + current->pid % num_stripes;
> +	switch(fs_info->fs_devices->readmirror_policy) {
> +	case BTRFS_READMIRROR_DEFAULT:
> +		/* fall through */
> +	default:
> +		/* readmirror as per thread pid */
> +		preferred_mirror = first + current->pid % num_stripes;
> +		break;
> +	}
>  
>  	if (dev_replace_is_ongoing &&
>  	    fs_info->dev_replace.cont_reading_from_srcdev_mode ==
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 7f6aa1816409..e985d2133c0a 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -219,6 +219,10 @@ BTRFS_DEVICE_GETSET_FUNCS(total_bytes);
>  BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
>  BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
>  
> +enum btrfs_readmirror_policy {
> +	BTRFS_READMIRROR_DEFAULT,
> +};
> +
>  struct btrfs_fs_devices {
>  	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
>  	u8 metadata_uuid[BTRFS_FSID_SIZE];
> @@ -269,6 +273,8 @@ struct btrfs_fs_devices {
>  	struct kobject fsid_kobj;
>  	struct kobject *device_dir_kobj;
>  	struct completion kobj_unregister;
> +
> +	int readmirror_policy;
>  };
>  
>  #define BTRFS_BIO_INLINE_CSUM_SIZE	64
> -- 
> 2.20.1 (Apple Git-117)
Anand Jain July 24, 2019, 2:42 a.m. UTC | #2
> On 23 Jul 2019, at 10:57 PM, David Sterba <dsterba@suse.cz> wrote:
> 
> On Wed, Jun 26, 2019 at 04:34:01PM +0800, Anand Jain wrote:
>> Function call chain  __btrfs_map_block()->find_live_mirror() uses
>> thread %pid to determine the %mirror_num for the read when mirror_num=0
>> in the argument.
>> 
>> This patch introduces a framework so that readmirror is a configurable
>> parameter, with default set to pid.
>> 
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>> fs/btrfs/props.c   | 41 +++++++++++++++++++++++++++++++++++++++++
>> fs/btrfs/volumes.c |  9 ++++++++-
>> fs/btrfs/volumes.h |  6 ++++++
>> 3 files changed, 55 insertions(+), 1 deletion(-)
>> 
>> diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
>> index f9143f7c006d..0dc26a154a98 100644
>> --- a/fs/btrfs/props.c
>> +++ b/fs/btrfs/props.c
>> @@ -10,6 +10,7 @@
>> #include "ctree.h"
>> #include "xattr.h"
>> #include "compression.h"
>> +#include "volumes.h"
>> 
>> #define BTRFS_PROP_HANDLERS_HT_BITS 8
>> static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
>> @@ -312,6 +313,39 @@ static const char *prop_compression_extract(struct inode *inode)
>> 	return NULL;
>> }
>> 
>> +static int prop_readmirror_validate(struct inode *inode, const char *value,
>> +				    size_t len)
>> +{
>> +	struct btrfs_root *root = BTRFS_I(inode)->root;
>> +
>> +	if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID)
>> +		return -EINVAL;
>> +
>> +	if (!len)
>> +		return 0;
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static int prop_readmirror_apply(struct inode *inode, const char *value,
>> +				 size_t len)
>> +{
>> +	struct btrfs_fs_devices *fs_devices = btrfs_sb(inode->i_sb)->fs_devices;
>> +
>> +	fs_devices->readmirror_policy = BTRFS_READMIRROR_DEFAULT;
>> +
>> +	return 0;
>> +}
>> +
>> +static const char *prop_readmirror_extract(struct inode *inode)
>> +{
>> +	/*
>> +	 * readmirror policy is applied for the whole FS, inheritance is not
>> +	 * applicable.
>> +	 */
> 
> Extract is the 'get' implementation of the property, not inheritance, or
> I don't understand what does the comment refer to.


prop_handler::extract() is only used by inherit_props(). Readmirror property is for the volume/fsid so prop_handler::inheritable is set to 0. So inherit_props() doesn’t call extract() for readmirror.
The getxattr still work using the xattr interface and will have to mount the root which is I think is ok which is similar to the admin only operations, otherwise we have to introduce a new ioctl.

Thanks, Anand


>> +	return NULL;
> 
> The return value should reflect the status of the property, ie.
> basically the same value that would set the current state.
> 
>> +}
>> +
>> static struct prop_handler prop_handlers[] = {
>> 	{
>> 		.xattr_name = XATTR_BTRFS_PREFIX "compression",
>> @@ -320,6 +354,13 @@ static struct prop_handler prop_handlers[] = {
>> 		.extract = prop_compression_extract,
>> 		.inheritable = 1
>> 	},
>> +	{
>> +		.xattr_name = XATTR_BTRFS_PREFIX "readmirror",
>> +		.validate = prop_readmirror_validate,
>> +		.apply = prop_readmirror_apply,
>> +		.extract = prop_readmirror_extract,
>> +		.inheritable = 0
>> +	},
>> };
>> 
>> static int inherit_props(struct btrfs_trans_handle *trans,
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index a13ddba1ebc3..d72850ed4f88 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -5490,7 +5490,14 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info,
>> 	else
>> 		num_stripes = map->num_stripes;
>> 
>> -	preferred_mirror = first + current->pid % num_stripes;
>> +	switch(fs_info->fs_devices->readmirror_policy) {
>> +	case BTRFS_READMIRROR_DEFAULT:
>> +		/* fall through */
>> +	default:
>> +		/* readmirror as per thread pid */
>> +		preferred_mirror = first + current->pid % num_stripes;
>> +		break;
>> +	}
>> 
>> 	if (dev_replace_is_ongoing &&
>> 	    fs_info->dev_replace.cont_reading_from_srcdev_mode ==
>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>> index 7f6aa1816409..e985d2133c0a 100644
>> --- a/fs/btrfs/volumes.h
>> +++ b/fs/btrfs/volumes.h
>> @@ -219,6 +219,10 @@ BTRFS_DEVICE_GETSET_FUNCS(total_bytes);
>> BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
>> BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
>> 
>> +enum btrfs_readmirror_policy {
>> +	BTRFS_READMIRROR_DEFAULT,
>> +};
>> +
>> struct btrfs_fs_devices {
>> 	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
>> 	u8 metadata_uuid[BTRFS_FSID_SIZE];
>> @@ -269,6 +273,8 @@ struct btrfs_fs_devices {
>> 	struct kobject fsid_kobj;
>> 	struct kobject *device_dir_kobj;
>> 	struct completion kobj_unregister;
>> +
>> +	int readmirror_policy;
>> };
>> 
>> #define BTRFS_BIO_INLINE_CSUM_SIZE	64
>> -- 
>> 2.20.1 (Apple Git-117)

Patch
diff mbox series

diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index f9143f7c006d..0dc26a154a98 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -10,6 +10,7 @@ 
 #include "ctree.h"
 #include "xattr.h"
 #include "compression.h"
+#include "volumes.h"
 
 #define BTRFS_PROP_HANDLERS_HT_BITS 8
 static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
@@ -312,6 +313,39 @@  static const char *prop_compression_extract(struct inode *inode)
 	return NULL;
 }
 
+static int prop_readmirror_validate(struct inode *inode, const char *value,
+				    size_t len)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+
+	if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID)
+		return -EINVAL;
+
+	if (!len)
+		return 0;
+
+	return -EINVAL;
+}
+
+static int prop_readmirror_apply(struct inode *inode, const char *value,
+				 size_t len)
+{
+	struct btrfs_fs_devices *fs_devices = btrfs_sb(inode->i_sb)->fs_devices;
+
+	fs_devices->readmirror_policy = BTRFS_READMIRROR_DEFAULT;
+
+	return 0;
+}
+
+static const char *prop_readmirror_extract(struct inode *inode)
+{
+	/*
+	 * readmirror policy is applied for the whole FS, inheritance is not
+	 * applicable.
+	 */
+	return NULL;
+}
+
 static struct prop_handler prop_handlers[] = {
 	{
 		.xattr_name = XATTR_BTRFS_PREFIX "compression",
@@ -320,6 +354,13 @@  static struct prop_handler prop_handlers[] = {
 		.extract = prop_compression_extract,
 		.inheritable = 1
 	},
+	{
+		.xattr_name = XATTR_BTRFS_PREFIX "readmirror",
+		.validate = prop_readmirror_validate,
+		.apply = prop_readmirror_apply,
+		.extract = prop_readmirror_extract,
+		.inheritable = 0
+	},
 };
 
 static int inherit_props(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a13ddba1ebc3..d72850ed4f88 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5490,7 +5490,14 @@  static int find_live_mirror(struct btrfs_fs_info *fs_info,
 	else
 		num_stripes = map->num_stripes;
 
-	preferred_mirror = first + current->pid % num_stripes;
+	switch(fs_info->fs_devices->readmirror_policy) {
+	case BTRFS_READMIRROR_DEFAULT:
+		/* fall through */
+	default:
+		/* readmirror as per thread pid */
+		preferred_mirror = first + current->pid % num_stripes;
+		break;
+	}
 
 	if (dev_replace_is_ongoing &&
 	    fs_info->dev_replace.cont_reading_from_srcdev_mode ==
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 7f6aa1816409..e985d2133c0a 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -219,6 +219,10 @@  BTRFS_DEVICE_GETSET_FUNCS(total_bytes);
 BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
 BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
 
+enum btrfs_readmirror_policy {
+	BTRFS_READMIRROR_DEFAULT,
+};
+
 struct btrfs_fs_devices {
 	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
 	u8 metadata_uuid[BTRFS_FSID_SIZE];
@@ -269,6 +273,8 @@  struct btrfs_fs_devices {
 	struct kobject fsid_kobj;
 	struct kobject *device_dir_kobj;
 	struct completion kobj_unregister;
+
+	int readmirror_policy;
 };
 
 #define BTRFS_BIO_INLINE_CSUM_SIZE	64