[Ocfs2-devel] [PATCH 1/1] Ocfs2: Add new OCFS2_IOC_INFO ioctl for ocfs2 v7.

[tristan]

Sunil Mushran wrote:
> Much better. Comments inlined.
>
> Tristan Ye wrote:
>> The reason why we need this ioctl is to offer the none-privileged
>> end-user a possibility to get filesys info gathering.
>>
>> We use OCFS2_IOC_INFO to manipulate the new ioctl, userspace passes a
>> structure to kernel containing an array of request pointers and request
>> count, such as,
>>
>> * From userspace:
>>
>> struct ocfs2_info_blocksize oib = {
>> .ib_req = {
>> .ir_magic = OCFS2_INFO_MAGIC,
>> .ir_code = OCFS2_INFO_BLOCKSIZE,
>> ...
>> }
>> ...
>> }
>>
>> struct ocfs2_info_clustersize oic = {
>> ...
>> }
>>
>> uint64_t reqs[2] = {(unsigned long)&oib,
>> (unsigned long)&oic};
>>
>> struct ocfs2_info info = {
>> .oi_requests = reqs,
>> .oi_count = 2,
>> }
>>
>> ret = ioctl(fd, OCFS2_IOC_INFO, &info);
>
>
> Can you add this description atop ocfs2_info_handle() too.
>
>
>> * In kernel:
>>
>> Get the request pointers from *info*, then handle each request one 
>> bye one.
>>
>> Idea here is to make the spearated request small enough to guarantee
>> a better backward&forward compatibility since a small piece of request
>> would be less likely to be broken if filesys on raw disk get changed.
>>
>> Currently, following 8 ioctls get implemented per the requirement from
>> userspace tool o2info, and I believe it will grow over time:-)
>>
>> OCFS2_INFO_CLUSTERSIZE
>> OCFS2_INFO_BLOCKSIZE
>> OCFS2_INFO_MAXSLOTS
>> OCFS2_INFO_LABEL
>> OCFS2_INFO_UUID
>> OCFS2_INFO_FS_FEATURES
>>
>> This ioctl is only specific to OCFS2.
>>
>> Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
>> ---
>> fs/ocfs2/ioctl.c | 281 ++++++++++++++++++++++++++++++++++++++++++++++++
>> fs/ocfs2/ocfs2_ioctl.h | 81 ++++++++++++++
>> 2 files changed, 362 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
>> index 7d9d9c1..930e3ba 100644
>> --- a/fs/ocfs2/ioctl.c
>> +++ b/fs/ocfs2/ioctl.c
>> @@ -23,8 +23,13 @@
>> #include "ioctl.h"
>> #include "resize.h"
>> #include "refcounttree.h"
>> +#include "sysfile.h"
>> +#include "buffer_head_io.h"
>> +#include "suballoc.h"
>> +
>>
>> #include <linux/ext2_fs.h>
>> +#include <linux/compat.h>
>>
>> static int ocfs2_get_inode_attr(struct inode *inode, unsigned *flags)
>> {
>> @@ -109,6 +114,268 @@ bail:
>> return status;
>> }
>>
>> +int ocfs2_info_handle_blocksize(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_blocksize oib;
>> +
>> + if (copy_from_user(&oib, req, sizeof(struct ocfs2_info_blocksize)))
>> + goto bail;
>> +
>> + oib.ib_blocksize = inode->i_sb->s_blocksize;
>> + oib.ib_req.ir_flags |= OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user((struct ocfs2_info_blocksize __user *)req, &oib,
>> + sizeof(struct ocfs2_info_blocksize)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>
> Why not use the error code returned by copy_from/to?
>
> + int status;
> + struct ocfs2_info_blocksize oib;
> +
> + status = o2info_copy_from_user(oib, req);
> + if (!status) {
> + oib.ib_blocksize = inode->i_sb->s_blocksize;
> + oib.ib_req.ir_flags |= OCFS2_INFO_FL_FILLED;
> + status = o2info_copy_to_user(oib, req);
> + }
> +
> + return status;


I agree on the idea about using macros to automatically handle the info 
type, however, I'd prefer to return -EFAULT instead of returning 
copy_from/to_user()'s ret code directly, since the ret code of these 
functions represent nothing but a number of failing bytes which has not 
been successfully transfered. Here we'd better return a real err code, 
and a -EFAULT makes more sense I guess.


>
>> +
>> +int ocfs2_info_handle_clustersize(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_clustersize oic;
>> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +
>> + if (copy_from_user(&oic, req, sizeof(struct ocfs2_info_clustersize)))
>> + goto bail;
>> +
>> + oic.ic_clustersize = osb->s_clustersize;
>> + oic.ic_req.ir_flags |= OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user((struct ocfs2_info_clustersize __user *)req, &oic,
>> + sizeof(struct ocfs2_info_clustersize)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle_maxslots(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_maxslots ois;
>> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +
>> + if (copy_from_user(&ois, req, sizeof(struct ocfs2_info_maxslots)))
>> + goto bail;
>> +
>> + ois.is_max_slots = osb->max_slots;
>> + ois.is_req.ir_flags |= OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user((struct ocfs2_info_maxslots __user *)req, &ois,
>> + sizeof(struct ocfs2_info_maxslots)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle_label(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_label oil;
>> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +
>> + if (copy_from_user(&oil, req, sizeof(struct ocfs2_info_label)))
>> + goto bail;
>> +
>> + memcpy(oil.il_label, osb->vol_label, OCFS2_MAX_VOL_LABEL_LEN);
>> + oil.il_req.ir_flags |= OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user((struct ocfs2_info_label __user *)req, &oil,
>> + sizeof(struct ocfs2_info_label)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle_uuid(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_uuid oiu;
>> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +
>> + if (copy_from_user(&oiu, req, sizeof(struct ocfs2_info_uuid)))
>> + goto bail;
>> +
>> + memcpy(oiu.iu_uuid_str, osb->uuid_str, OCFS2_INFO_VOL_UUIDSTR_LEN);
>> + oiu.iu_req.ir_flags |= OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user((struct ocfs2_info_uuid __user *)req, &oiu,
>> + sizeof(struct ocfs2_info_uuid)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle_fs_features(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_fs_features oif;
>> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +
>> + if (copy_from_user(&oif, req, sizeof(struct ocfs2_info_fs_features)))
>> + goto bail;
>> +
>> + oif.if_compat_features = osb->s_feature_compat;
>> + oif.if_incompat_features = osb->s_feature_incompat;
>> + oif.if_ro_compat_features = osb->s_feature_ro_compat;
>> + oif.if_req.ir_flags |= OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user((struct ocfs2_info_fs_features __user *)req, &oif,
>> + sizeof(struct ocfs2_info_fs_features)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle_unknown(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = -EFAULT;
>> + struct ocfs2_info_request oir;
>> +
>> + if (copy_from_user(&oir, req, sizeof(struct ocfs2_info_request)))
>> + goto bail;
>> +
>> + oir.ir_flags &= ~OCFS2_INFO_FL_FILLED;
>> +
>> + if (copy_to_user(req, &oir, sizeof(struct ocfs2_info_request)))
>> + goto bail;
>> +
>> + status = 0;
>> +bail:
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle_request(struct inode *inode,
>> + struct ocfs2_info_request __user *req)
>> +{
>> + int status = 0;
>> + struct ocfs2_info_request oir;
>> +
>> + if (copy_from_user(&oir, req, sizeof(struct ocfs2_info_request))) {
>> + status = -EFAULT;
>> + goto bail;
>> + }
>> +
>> + if (oir.ir_magic != OCFS2_INFO_MAGIC) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> +
>
> status = -EINVAL;
>
>> + switch (oir.ir_code) {
>> + case OCFS2_INFO_BLOCKSIZE:
>> + if (oir.ir_size != sizeof(struct ocfs2_info_blocksize)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> + status = ocfs2_info_handle_blocksize(inode, req);
>> + break;
>
> + case OCFS2_INFO_BLOCKSIZE:
> + if (oir.ir_size == sizeof(struct ocfs2_info_blocksize))
> + status = ocfs2_info_handle_blocksize(inode, req);
> + break;
>
> Do same below.
>
>
>> + case OCFS2_INFO_CLUSTERSIZE:
>> + if (oir.ir_size != sizeof(struct ocfs2_info_clustersize)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> + status = ocfs2_info_handle_clustersize(inode, req);
>> + break;
>> + case OCFS2_INFO_MAXSLOTS:
>> + if (oir.ir_size != sizeof(struct ocfs2_info_maxslots)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> + status = ocfs2_info_handle_maxslots(inode, req);
>> + break;
>> + case OCFS2_INFO_LABEL:
>> + if (oir.ir_size != sizeof(struct ocfs2_info_label)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> + status = ocfs2_info_handle_label(inode, req);
>> + break;
>> + case OCFS2_INFO_UUID:
>> + if (oir.ir_size != sizeof(struct ocfs2_info_uuid)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> + status = ocfs2_info_handle_uuid(inode, req);
>> + break;
>> + case OCFS2_INFO_FS_FEATURES:
>> + if (oir.ir_size != sizeof(struct ocfs2_info_fs_features)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> + status = ocfs2_info_handle_fs_features(inode, req);
>> + break;
>> + default:
>> + status = ocfs2_info_handle_unknown(inode, req);
>> + break;
>> + }
>> +
>> +bail:
>> + mlog_exit(status);
>
> No need for mlog.
>
>> + return status;
>> +}
>> +
>> +int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
>> + int compat_flag)
>> +{
>> + int i, status = 0;
>> + u64 req_addr;
>> + struct ocfs2_info_request __user *reqp;
>> +
>> + if ((info->oi_count > OCFS2_INFO_MAX_REQUEST) ||
>> + (!info->oi_requests)) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> +
>> + for (i = 0; i < info->oi_count; i++) {
>> + status = -EFAULT;
>> + if (compat_flag) {
>> + if (get_user(req_addr,
>> + (u64 __user *)compat_ptr(info->oi_requests) + i))
>> + goto bail;
>> + } else {
>> + if (get_user(req_addr,
>> + (u64 __user *)(info->oi_requests) + i))
>> + goto bail;
>> + }
>> +
>> + reqp = (struct ocfs2_info_request *)req_addr;
>> + if (!reqp) {
>> + status = -EINVAL;
>> + goto bail;
>> + }
>> +
>> + status = ocfs2_info_handle_request(inode, reqp);
>> + if (status)
>> + goto bail;
>> + }
>> +
>> +bail:
>> + mlog_exit(status);
>
> Remove mlog.
>
>> + return status;
>> +}
>> +
>> long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>> {
>> struct inode *inode = filp->f_path.dentry->d_inode;
>> @@ -120,6 +387,7 @@ long ocfs2_ioctl(struct file *filp, unsigned int 
>> cmd, unsigned long arg)
>> struct reflink_arguments args;
>> const char *old_path, *new_path;
>> bool preserve;
>> + struct ocfs2_info info;
>>
>> switch (cmd) {
>> case OCFS2_IOC_GETFLAGS:
>> @@ -174,6 +442,12 @@ long ocfs2_ioctl(struct file *filp, unsigned int 
>> cmd, unsigned long arg)
>> preserve = (args.preserve != 0);
>>
>> return ocfs2_reflink_ioctl(inode, old_path, new_path, preserve);
>> + case OCFS2_IOC_INFO:
>> + if (copy_from_user(&info, (struct ocfs2_info __user *)arg,
>> + sizeof(struct ocfs2_info)))
>> + return -EFAULT;
>> +
>> + return ocfs2_info_handle(inode, &info, 0);
>> default:
>> return -ENOTTY;
>> }
>> @@ -185,6 +459,7 @@ long ocfs2_compat_ioctl(struct file *file, 
>> unsigned cmd, unsigned long arg)
>> bool preserve;
>> struct reflink_arguments args;
>> struct inode *inode = file->f_path.dentry->d_inode;
>> + struct ocfs2_info info;
>>
>> switch (cmd) {
>> case OCFS2_IOC32_GETFLAGS:
>> @@ -209,6 +484,12 @@ long ocfs2_compat_ioctl(struct file *file, 
>> unsigned cmd, unsigned long arg)
>>
>> return ocfs2_reflink_ioctl(inode, compat_ptr(args.old_path),
>> compat_ptr(args.new_path), preserve);
>> + case OCFS2_IOC_INFO:
>> + if (copy_from_user(&info, (struct ocfs2_info __user *)arg,
>> + sizeof(struct ocfs2_info)))
>> + return -EFAULT;
>> +
>> + return ocfs2_info_handle(inode, &info, 1);
>> default:
>> return -ENOIOCTLCMD;
>> }
>> diff --git a/fs/ocfs2/ocfs2_ioctl.h b/fs/ocfs2/ocfs2_ioctl.h
>> index 2d3420a..50f237a 100644
>> --- a/fs/ocfs2/ocfs2_ioctl.h
>> +++ b/fs/ocfs2/ocfs2_ioctl.h
>> @@ -76,4 +76,85 @@ struct reflink_arguments {
>> };
>> #define OCFS2_IOC_REFLINK _IOW('o', 4, struct reflink_arguments)
>>
>> +/* Following definitions dedicated for ocfs2_info_request ioctls. */
>> +#define OCFS2_INFO_VOL_UUIDSTR_LEN (OCFS2_VOL_UUID_LEN * 2 + 1)
>> +#define OCFS2_INFO_MAX_REQUEST (50)
>> +
>> +/* Magic number of all requests */
>> +#define OCFS2_INFO_MAGIC (0x4F32494E)
>> +
>> +/*
>> + * Always try to separate info request into small pieces to
>> + * guarantee the backward&forward compatibility.
>> + */
>> +struct ocfs2_info {
>> + __u64 oi_requests; /* Array of __u64 pointers to requests */
>> + __u32 oi_count; /* Number of requests in info_requests */
>> +};
>> +
>> +struct ocfs2_info_request {
>> +/*00*/ __u32 ir_magic; /* Magic number */
>> + __u32 ir_code; /* Info request code */
>> + __u32 ir_size; /* Size of request */
>> + __u32 ir_flags; /* Request flags */
>> +/*10*/ /* Request specific fields */
>> +};
>> +
>> +struct ocfs2_info_clustersize {
>> + struct ocfs2_info_request ic_req;
>> + __u32 ic_clustersize;
>> +};
>> +
>> +struct ocfs2_info_blocksize {
>> + struct ocfs2_info_request ib_req;
>> + __u32 ib_blocksize;
>> +};
>> +
>> +struct ocfs2_info_maxslots {
>> + struct ocfs2_info_request is_req;
>> + __u16 is_max_slots;
>> +};
>> +
>> +struct ocfs2_info_label {
>> + struct ocfs2_info_request il_req;
>> + __u8 il_label[OCFS2_MAX_VOL_LABEL_LEN];
>> +};
>> +
>> +struct ocfs2_info_uuid {
>> + struct ocfs2_info_request iu_req;
>> + __u8 iu_uuid_str[OCFS2_INFO_VOL_UUIDSTR_LEN];
>> +};
>> +
>> +struct ocfs2_info_fs_features {
>> + struct ocfs2_info_request if_req;
>> + __u32 if_compat_features;
>> + __u32 if_incompat_features;
>> + __u32 if_ro_compat_features;
>> +};
>> +
>> +/* Codes for ocfs2_info_request */
>> +enum ocfs2_info_type {
>> + OCFS2_INFO_CLUSTERSIZE = 1,
>> + OCFS2_INFO_BLOCKSIZE,
>> + OCFS2_INFO_MAXSLOTS,
>> + OCFS2_INFO_LABEL,
>> + OCFS2_INFO_UUID,
>> + OCFS2_INFO_FS_FEATURES,
>> + OCFS2_INFO_NUM_TYPES
>> +};
>> +
>> +/* Flags for struct ocfs2_info_request */
>> +/* Filled by the caller */
>> +#define OCFS2_INFO_FL_NON_COHERENT (0x00000001) /* Cluster coherency 
>> not
>> + required. This is a hint.
>> + It is up to ocfs2 whether
>> + the request can be fulfilled
>> + without locking. */
>> +/* Filled by ocfs2 */
>> +#define OCFS2_INFO_FL_FILLED (0x80000000) /* Filesystem understood
>> + this request and
>> + filled in the answer */
>> +
>> +#define OCFS2_IOC_INFO _IOR('o', 5, struct ocfs2_info)
>> +
>> #endif /* OCFS2_IOCTL_H */
>