[PATCH v2 13/38] cxlflash: Support adapter file descriptors for OCXL

Uma Krishnan ukrishn at linux.vnet.ibm.com
Sat Mar 24 04:45:21 AEDT 2018



> On Mar 22, 2018, at 12:12 PM, Frederic Barrat <fbarrat at linux.vnet.ibm.com> wrote:
> 
> 
> 
> Le 26/02/2018 à 23:21, Uma Krishnan a écrit :
>> Allocate a file descriptor for an adapter context when requested. In order
>> to allocate inodes for the file descriptors, a pseudo filesystem is created
>> and used.
>> Signed-off-by: Uma Krishnan <ukrishn at linux.vnet.ibm.com>
>> Acked-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>
>> ---
> 
> 
> We've touched the subject before, and I don't have a magic solution, but it feels like something could be shared here with cxl, or maybe even other drivers?
> 
Yes, perhaps we could look at refactoring in a future series.

> I only took a quick read of the inode allocator.
> 
>  Fred
> 
> 
> 
> 
>>  drivers/scsi/cxlflash/ocxl_hw.c | 200 ++++++++++++++++++++++++++++++++++++++++
>>  drivers/scsi/cxlflash/ocxl_hw.h |   1 +
>>  2 files changed, 201 insertions(+)
>> diff --git a/drivers/scsi/cxlflash/ocxl_hw.c b/drivers/scsi/cxlflash/ocxl_hw.c
>> index 6472210..59e9003 100644
>> --- a/drivers/scsi/cxlflash/ocxl_hw.c
>> +++ b/drivers/scsi/cxlflash/ocxl_hw.c
>> @@ -12,13 +12,144 @@
>>   * 2 of the License, or (at your option) any later version.
>>   */
>> +#include <linux/file.h>
>>  #include <linux/idr.h>
>> +#include <linux/module.h>
>> +#include <linux/mount.h>
>>  #include <misc/ocxl.h>
>>  #include "backend.h"
>>  #include "ocxl_hw.h"
>> +/*
>> + * Pseudo-filesystem to allocate inodes.
>> + */
>> +
>> +#define OCXLFLASH_FS_MAGIC      0x1697698f
>> +
>> +static int ocxlflash_fs_cnt;
>> +static struct vfsmount *ocxlflash_vfs_mount;
>> +
>> +static const struct dentry_operations ocxlflash_fs_dops = {
>> +	.d_dname	= simple_dname,
>> +};
>> +
>> +/*
>> + * ocxlflash_fs_mount() - mount the pseudo-filesystem
>> + * @fs_type:	File system type.
>> + * @flags:	Flags for the filesystem.
>> + * @dev_name:	Device name associated with the filesystem.
>> + * @data:	Data pointer.
>> + *
>> + * Return: pointer to the directory entry structure
>> + */
>> +static struct dentry *ocxlflash_fs_mount(struct file_system_type *fs_type,
>> +					 int flags, const char *dev_name,
>> +					 void *data)
>> +{
>> +	return mount_pseudo(fs_type, "ocxlflash:", NULL, &ocxlflash_fs_dops,
>> +			    OCXLFLASH_FS_MAGIC);
>> +}
>> +
>> +static struct file_system_type ocxlflash_fs_type = {
>> +	.name		= "ocxlflash",
>> +	.owner		= THIS_MODULE,
>> +	.mount		= ocxlflash_fs_mount,
>> +	.kill_sb	= kill_anon_super,
>> +};
>> +
>> +/*
>> + * ocxlflash_release_mapping() - release the memory mapping
>> + * @ctx:	Context whose mapping is to be released.
>> + */
>> +static void ocxlflash_release_mapping(struct ocxlflash_context *ctx)
>> +{
>> +	if (ctx->mapping)
>> +		simple_release_fs(&ocxlflash_vfs_mount, &ocxlflash_fs_cnt);
>> +	ctx->mapping = NULL;
>> +}
>> +
>> +/*
>> + * ocxlflash_getfile() - allocate pseudo filesystem, inode, and the file
>> + * @dev:	Generic device of the host.
>> + * @name:	Name of the pseudo filesystem.
>> + * @fops:	File operations.
>> + * @priv:	Private data.
>> + * @flags:	Flags for the file.
>> + *
>> + * Return: pointer to the file on success, ERR_PTR on failure
>> + */
>> +static struct file *ocxlflash_getfile(struct device *dev, const char *name,
>> +				      const struct file_operations *fops,
>> +				      void *priv, int flags)
>> +{
>> +	struct qstr this;
>> +	struct path path;
>> +	struct file *file;
>> +	struct inode *inode = NULL;
>> +	int rc;
>> +
>> +	if (fops->owner && !try_module_get(fops->owner)) {
>> +		dev_err(dev, "%s: Owner does not exist\n", __func__);
>> +		rc = -ENOENT;
>> +		goto err1;
>> +	}
>> +
>> +	rc = simple_pin_fs(&ocxlflash_fs_type, &ocxlflash_vfs_mount,
>> +			   &ocxlflash_fs_cnt);
>> +	if (unlikely(rc < 0)) {
>> +		dev_err(dev, "%s: Cannot mount ocxlflash pseudofs rc=%d\n",
>> +			__func__, rc);
>> +		goto err2;
>> +	}
>> +
>> +	inode = alloc_anon_inode(ocxlflash_vfs_mount->mnt_sb);
>> +	if (IS_ERR(inode)) {
>> +		rc = PTR_ERR(inode);
>> +		dev_err(dev, "%s: alloc_anon_inode failed rc=%d\n",
>> +			__func__, rc);
>> +		goto err3;
>> +	}
>> +
>> +	this.name = name;
>> +	this.len = strlen(name);
>> +	this.hash = 0;
>> +	path.dentry = d_alloc_pseudo(ocxlflash_vfs_mount->mnt_sb, &this);
>> +	if (!path.dentry) {
>> +		dev_err(dev, "%s: d_alloc_pseudo failed\n", __func__);
>> +		rc = -ENOMEM;
>> +		goto err4;
>> +	}
>> +
>> +	path.mnt = mntget(ocxlflash_vfs_mount);
>> +	d_instantiate(path.dentry, inode);
>> +
>> +	file = alloc_file(&path, OPEN_FMODE(flags), fops);
>> +	if (IS_ERR(file)) {
>> +		rc = PTR_ERR(file);
>> +		dev_err(dev, "%s: alloc_file failed rc=%d\n",
>> +			__func__, rc);
>> +		goto err5;
>> +	}
>> +
>> +	file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
>> +	file->private_data = priv;
>> +out:
>> +	return file;
>> +err5:
>> +	path_put(&path);
>> +err4:
>> +	iput(inode);
>> +err3:
>> +	simple_release_fs(&ocxlflash_vfs_mount, &ocxlflash_fs_cnt);
>> +err2:
>> +	module_put(fops->owner);
>> +err1:
>> +	file = ERR_PTR(rc);
>> +	goto out;
>> +}
>> +
>>  /**
>>   * ocxlflash_set_master() - sets the context as master
>>   * @ctx_cookie:	Adapter context to set as master.
>> @@ -75,6 +206,7 @@ static void *ocxlflash_dev_context_init(struct pci_dev *pdev, void *afu_cookie)
>>  	ctx->pe = rc;
>>  	ctx->master = false;
>> +	ctx->mapping = NULL;
>>  	ctx->hw_afu = afu;
>>  out:
>>  	return ctx;
>> @@ -100,6 +232,7 @@ static int ocxlflash_release_context(void *ctx_cookie)
>>  		goto out;
>>  	idr_remove(&ctx->hw_afu->idr, ctx->pe);
>> +	ocxlflash_release_mapping(ctx);
>>  	kfree(ctx);
>>  out:
>>  	return rc;
>> @@ -262,6 +395,72 @@ static void *ocxlflash_create_afu(struct pci_dev *pdev)
>>  	goto out;
>>  }
>> +static const struct file_operations ocxl_afu_fops = {
>> +	.owner		= THIS_MODULE,
>> +};
>> +
>> +/**
>> + * ocxlflash_get_fd() - get file descriptor for an adapter context
>> + * @ctx_cookie:	Adapter context.
>> + * @fops:	File operations to be associated.
>> + * @fd:		File descriptor to be returned back.
>> + *
>> + * Return: pointer to the file on success, ERR_PTR on failure
>> + */
>> +static struct file *ocxlflash_get_fd(void *ctx_cookie,
>> +				     struct file_operations *fops, int *fd)
>> +{
>> +	struct ocxlflash_context *ctx = ctx_cookie;
>> +	struct device *dev = ctx->hw_afu->dev;
>> +	struct file *file;
>> +	int flags, fdtmp;
>> +	int rc = 0;
>> +	char *name = NULL;
>> +
>> +	/* Only allow one fd per context */
>> +	if (ctx->mapping) {
>> +		dev_err(dev, "%s: Context is already mapped to an fd\n",
>> +			__func__);
>> +		rc = -EEXIST;
>> +		goto err1;
>> +	}
>> +
>> +	flags = O_RDWR | O_CLOEXEC;
>> +
>> +	/* This code is similar to anon_inode_getfd() */
>> +	rc = get_unused_fd_flags(flags);
>> +	if (unlikely(rc < 0)) {
>> +		dev_err(dev, "%s: get_unused_fd_flags failed rc=%d\n",
>> +			__func__, rc);
>> +		goto err1;
>> +	}
>> +	fdtmp = rc;
>> +
>> +	/* Use default ops if there is no fops */
>> +	if (!fops)
>> +		fops = (struct file_operations *)&ocxl_afu_fops;
>> +
>> +	name = kasprintf(GFP_KERNEL, "ocxlflash:%d", ctx->pe);
>> +	file = ocxlflash_getfile(dev, name, fops, ctx, flags);
>> +	kfree(name);
>> +	if (IS_ERR(file)) {
>> +		rc = PTR_ERR(file);
>> +		dev_err(dev, "%s: ocxlflash_getfile failed rc=%d\n",
>> +			__func__, rc);
>> +		goto err2;
>> +	}
>> +
>> +	ctx->mapping = file->f_mapping;
>> +	*fd = fdtmp;
>> +out:
>> +	return file;
>> +err2:
>> +	put_unused_fd(fdtmp);
>> +err1:
>> +	file = ERR_PTR(rc);
>> +	goto out;
>> +}
>> +
>>  /* Backend ops to ocxlflash services */
>>  const struct cxlflash_backend_ops cxlflash_ocxl_ops = {
>>  	.module			= THIS_MODULE,
>> @@ -271,4 +470,5 @@ const struct cxlflash_backend_ops cxlflash_ocxl_ops = {
>>  	.release_context	= ocxlflash_release_context,
>>  	.create_afu		= ocxlflash_create_afu,
>>  	.destroy_afu		= ocxlflash_destroy_afu,
>> +	.get_fd			= ocxlflash_get_fd,
>>  };
>> diff --git a/drivers/scsi/cxlflash/ocxl_hw.h b/drivers/scsi/cxlflash/ocxl_hw.h
>> index 0381682..7abc532 100644
>> --- a/drivers/scsi/cxlflash/ocxl_hw.h
>> +++ b/drivers/scsi/cxlflash/ocxl_hw.h
>> @@ -32,6 +32,7 @@ struct ocxl_hw_afu {
>>  struct ocxlflash_context {
>>  	struct ocxl_hw_afu *hw_afu;	/* HW AFU back pointer */
>> +	struct address_space *mapping;	/* Mapping for pseudo filesystem */
>>  	bool master;			/* Whether this is a master context */
>>  	int pe;				/* Process element */
>>  };



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