fscache: Attach the index key and aux data to the cookie

			const void *parent_netfs_data,

			const void *cookie_netfs_data);

		uint16_t (*get_key)(const void *cookie_netfs_data,

				    void *buffer,

				    uint16_t bufmax);

		void (*get_attr)(const void *cookie_netfs_data,

				 uint64_t *size);

		uint16_t (*get_aux)(const void *cookie_netfs_data,

				    void *buffer,

				    uint16_t bufmax);

		enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,

						   const void *data,

						   uint16_t datalen);

     cache in the parent's list will be chosen, or failing that, the first

     cache in the master list.

 (4) A function to retrieve an object's key from the netfs [mandatory].

     This function will be called with the netfs data that was passed to the

     cookie acquisition function and the maximum length of key data that it may

     provide.  It should write the required key data into the given buffer and

     return the quantity it wrote.

 (5) A function to retrieve attribute data from the netfs [optional].

 (4) A function to retrieve attribute data from the netfs [optional].

     This function will be called with the netfs data that was passed to the

     cookie acquisition function.  It should return the size of the file if

     If the function is absent, a file size of 0 is assumed.

 (6) A function to retrieve auxiliary data from the netfs [optional].

     This function will be called with the netfs data that was passed to the

     cookie acquisition function and the maximum length of auxiliary data that

     it may provide.  It should write the auxiliary data into the given buffer

     and return the quantity it wrote.

     If this function is absent, the auxiliary data length will be set to 0.

     The length of the auxiliary data buffer may be dependent on the key

     length.  A netfs mustn't rely on being able to provide more than 400 bytes

     for both.

 (7) A function to check the auxiliary data [optional].

 (5) A function to check the auxiliary data [optional].

     This function will be called to check that a match found in the cache for

     this object is valid.  For instance with AFS it could check the auxiliary

     This function can also be used to extract data from the auxiliary data in

     the cache and copy it into the netfs's structures.

 (8) A pair of functions to manage contexts for the completion callback

 (6) A pair of functions to manage contexts for the completion callback

     [optional].

     The cache read/write functions are passed a context which is then passed

     required for indices as indices may not contain data.  These functions may

     be called in interrupt context and so may not sleep.

 (9) A function to mark a page as retaining cache metadata [optional].

 (7) A function to mark a page as retaining cache metadata [optional].

     This is called by the cache to indicate that it is retaining in-memory

     information for this page and that the netfs should uncache the page when

     This function is not required for indices as they're not permitted data.

(10) A function to unmark all the pages retaining cache metadata [mandatory].

 (8) A function to unmark all the pages retaining cache metadata [mandatory].

     This is called by FS-Cache to indicate that a backing store is being

     unbound from a cookie and that all the marks on the pages should be

	struct fscache_cookie *

	fscache_acquire_cookie(struct fscache_cookie *parent,

			       const struct fscache_object_def *def,

			       const void *index_key,

			       size_t index_key_len,

			       const void *aux_data,

			       size_t aux_data_len,

			       void *netfs_data,

			       bool enable);

This function creates an index entry in the index represented by parent,

filling in the index entry by calling the operations pointed to by def.

A unique key that represents the object within the parent must be pointed to by

index_key and is of length index_key_len.

An optional blob of auxiliary data that is to be stored within the cache can be

pointed to with aux_data and should be of length aux_data_len.  This would

typically be used for storing coherency data.

The netfs may pass an arbitrary value in netfs_data and this will be presented

to it in the event of any calling back.  This may also be used in tracing or

logging of messages.

Note that this function never returns an error - all errors are handled

internally.  It may, however, return NULL to indicate no cookie.  It is quite

acceptable to pass this token back to this function as the parent to another

calling fscache_enable_cookie() (see below).

For example, with AFS, a cell would be added to the primary index.  This index

entry would have a dependent inode containing a volume location index for the

volume mappings within this cell:

entry would have a dependent inode containing volume mappings within this cell:

	cell->cache =

		fscache_acquire_cookie(afs_cache_netfs.primary_index,

				       &afs_cell_cache_index_def,

				       cell->name, strlen(cell->name),

				       NULL, 0,

				       cell, true);

Then when a volume location was accessed, it would be entered into the cell's

index and an inode would be allocated that acts as a volume type and hash chain

combination:

	vlocation->cache =

		fscache_acquire_cookie(cell->cache,

				       &afs_vlocation_cache_index_def,

				       vlocation, true);

And then a particular flavour of volume (R/O for example) could be added to

that index, creating another index for vnodes (AFS inode equivalents):

And then a particular volume could be added to that index by ID, creating

another index for vnodes (AFS inode equivalents):

	volume->cache =

		fscache_acquire_cookie(vlocation->cache,

		fscache_acquire_cookie(volume->cell->cache,

				       &afs_volume_cache_index_def,

				       &volume->vid, sizeof(volume->vid),

				       NULL, 0,

				       volume, true);

	vnode->cache =

		fscache_acquire_cookie(volume->cache,

				       &afs_vnode_cache_object_def,

				       &key, sizeof(key),

				       &aux, sizeof(aux),

				       vnode, true);

	xattr->cache =

		fscache_acquire_cookie(vnode->cache,

				       &afs_xattr_cache_object_def,

				       &xattr->name, strlen(xattr->name),

				       NULL, 0,

				       xattr, true);

Miscellaneous objects might be used to store extended attributes or directory

To find out whether auxiliary data for an object is up to data within the

cache, the following function can be called:

	int fscache_check_consistency(struct fscache_cookie *cookie)

	int fscache_check_consistency(struct fscache_cookie *cookie,

				      const void *aux_data);

This will call back to the netfs to check whether the auxiliary data associated

with a cookie is correct.  It returns 0 if it is and -ESTALE if it isn't; it

may also return -ENOMEM and -ERESTARTSYS.

with a cookie is correct; if aux_data is non-NULL, it will update the auxiliary

data buffer first.  It returns 0 if it is and -ESTALE if it isn't; it may also

return -ENOMEM and -ERESTARTSYS.

To request an update of the index data for an index or other object, the

following function should be called:

	void fscache_update_cookie(struct fscache_cookie *cookie);

	void fscache_update_cookie(struct fscache_cookie *cookie,

				   const void *aux_data);

This function will refer back to the netfs_data pointer stored in the cookie by

the acquisition function to obtain the data to write into each revised index

entry.  The update method in the parent index definition will be called to

transfer the data.

This function will update the cookie's auxiliary data buffer from aux_data if

that is non-NULL and then schedule this to be stored on disk.  The update

method in the parent index definition will be called to transfer the data.

Note that partial updates may happen automatically at other times, such as when

data blocks are added to a data file object.

can be enabled or disabled later.  To disable a cookie, call:

	void fscache_disable_cookie(struct fscache_cookie *cookie,

				    const void *aux_data,

    				    bool invalidate);

If the cookie is not already disabled, this locks the cookie against other

Cookies can be enabled or reenabled with:

    	void fscache_enable_cookie(struct fscache_cookie *cookie,

				   const void *aux_data,

    				   bool (*can_enable)(void *data),

    				   void *data)

All possible failures are handled internally.  The cookie will only be marked

as enabled if provisional backing objects are allocated.

In both cases, the cookie's auxiliary data buffer is updated from aux_data if

that is non-NULL inside the enablement lock before proceeding.

===============================

MISCELLANEOUS COOKIE OPERATIONS

To get rid of a cookie, this function should be called.

	void fscache_relinquish_cookie(struct fscache_cookie *cookie,

				       const void *aux_data,

				       bool retire);

If retire is non-zero, then the object will be marked for recycling, and all

acquisition function is called.  Retirement here will overrule the pinning on a

cookie.

The cookie's auxiliary data will be updated from aux_data if that is non-NULL

so that the cache can lazily update it on disk.

One very important note - relinquish must NOT be called for a cookie unless all

the cookies for "child" indices, objects and pages have been relinquished

first.

	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);

}

static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,

					   void *buffer, uint16_t bufmax)

{

	struct v9fs_session_info *v9ses;

	uint16_t klen = 0;

	v9ses = (struct v9fs_session_info *)cookie_netfs_data;

	p9_debug(P9_DEBUG_FSC, "session %p buf %p size %u\n",

		 v9ses, buffer, bufmax);

	if (v9ses->cachetag)

		klen = strlen(v9ses->cachetag);

	if (klen > bufmax)

		return 0;

	memcpy(buffer, v9ses->cachetag, klen);

	p9_debug(P9_DEBUG_FSC, "cache session tag %s\n", v9ses->cachetag);

	return klen;

}

const struct fscache_cookie_def v9fs_cache_session_index_def = {

	.name		= "9P.session",

	.type		= FSCACHE_COOKIE_TYPE_INDEX,

	.get_key	= v9fs_cache_session_get_key,

};

void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)

{

	/* If no cache session tag was specified, we generate a random one. */

	if (!v9ses->cachetag)

		v9fs_random_cachetag(v9ses);

	if (!v9ses->cachetag) {

		if (v9fs_random_cachetag(v9ses) < 0) {

			v9ses->fscache = NULL;

			return;

		}

	}

	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,

						&v9fs_cache_session_index_def,

						v9ses->cachetag,

						strlen(v9ses->cachetag),

						NULL, 0,

						v9ses, true);

	p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",

		 v9ses, v9ses->fscache);

{

	p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",

		 v9ses, v9ses->fscache);

	fscache_relinquish_cookie(v9ses->fscache, 0);

	fscache_relinquish_cookie(v9ses->fscache, NULL, false);

	v9ses->fscache = NULL;

}

static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,

					 void *buffer, uint16_t bufmax)

{

	const struct v9fs_inode *v9inode = cookie_netfs_data;

	memcpy(buffer, &v9inode->qid.path, sizeof(v9inode->qid.path));

	p9_debug(P9_DEBUG_FSC, "inode %p get key %llu\n",

		 &v9inode->vfs_inode, v9inode->qid.path);

	return sizeof(v9inode->qid.path);

}

static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,

				      uint64_t *size)

{

		 &v9inode->vfs_inode, *size);

}

static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,

					 void *buffer, uint16_t buflen)

{

	const struct v9fs_inode *v9inode = cookie_netfs_data;

	memcpy(buffer, &v9inode->qid.version, sizeof(v9inode->qid.version));

	p9_debug(P9_DEBUG_FSC, "inode %p get aux %u\n",

		 &v9inode->vfs_inode, v9inode->qid.version);

	return sizeof(v9inode->qid.version);

}

static enum

fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,

					    const void *buffer,

const struct fscache_cookie_def v9fs_cache_inode_index_def = {

	.name		= "9p.inode",

	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,

	.get_key	= v9fs_cache_inode_get_key,

	.get_attr	= v9fs_cache_inode_get_attr,

	.get_aux	= v9fs_cache_inode_get_aux,

	.check_aux	= v9fs_cache_inode_check_aux,

};

	v9ses = v9fs_inode2v9ses(inode);

	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,

						  &v9fs_cache_inode_index_def,

						  &v9inode->qid.path,

						  sizeof(v9inode->qid.path),

						  &v9inode->qid.version,

						  sizeof(v9inode->qid.version),

						  v9inode, true);

	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",

	p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",

		 inode, v9inode->fscache);

	fscache_relinquish_cookie(v9inode->fscache, 0);

	fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,

				  false);

	v9inode->fscache = NULL;

}

	p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",

		 inode, v9inode->fscache);

	fscache_relinquish_cookie(v9inode->fscache, 1);

	fscache_relinquish_cookie(v9inode->fscache, NULL, true);

	v9inode->fscache = NULL;

}

	old = v9inode->fscache;

	mutex_lock(&v9inode->fscache_lock);

	fscache_relinquish_cookie(v9inode->fscache, 1);

	fscache_relinquish_cookie(v9inode->fscache, NULL, true);

	v9ses = v9fs_inode2v9ses(inode);

	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,

						  &v9fs_cache_inode_index_def,

						  &v9inode->qid.path,

						  sizeof(v9inode->qid.path),

						  &v9inode->qid.version,

						  sizeof(v9inode->qid.version),

						  v9inode, true);

	p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",

		 inode, old, v9inode->fscache);

#include <linux/sched.h>

#include "internal.h"

static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,

				       void *buffer, uint16_t buflen);

static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,

					 void *buffer, uint16_t buflen);

static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,

					void *buffer, uint16_t buflen);

static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,

				     uint64_t *size);

static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,

					void *buffer, uint16_t buflen);

static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,

						       const void *buffer,

						       uint16_t buflen);

struct fscache_cookie_def afs_cell_cache_index_def = {

	.name		= "AFS.cell",

	.type		= FSCACHE_COOKIE_TYPE_INDEX,

	.get_key	= afs_cell_cache_get_key,

};

struct fscache_cookie_def afs_volume_cache_index_def = {

	.name		= "AFS.volume",

	.type		= FSCACHE_COOKIE_TYPE_INDEX,

	.get_key	= afs_volume_cache_get_key,

};

struct fscache_cookie_def afs_vnode_cache_index_def = {

	.name		= "AFS.vnode",

	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,

	.get_key		= afs_vnode_cache_get_key,

	.get_attr	= afs_vnode_cache_get_attr,

	.get_aux		= afs_vnode_cache_get_aux,

	.check_aux	= afs_vnode_cache_check_aux,

};

/*

 * set the key for the index entry

 */

static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,

				       void *buffer, uint16_t bufmax)

{

	const struct afs_cell *cell = cookie_netfs_data;

	uint16_t klen;

	_enter("%p,%p,%u", cell, buffer, bufmax);

	klen = strlen(cell->name);

	if (klen > bufmax)

		return 0;

	memcpy(buffer, cell->name, klen);

	return klen;

}

/*****************************************************************************/

/*

 * set the key for the volume index entry

 */

static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,

					 void *buffer, uint16_t bufmax)

{

	const struct afs_volume *volume = cookie_netfs_data;

	struct {

		u64 volid;

	} __packed key;

	_enter("{%u},%p,%u", volume->type, buffer, bufmax);

	if (bufmax < sizeof(key))

		return 0;

	key.volid = volume->vid;

	memcpy(buffer, &key, sizeof(key));

	return sizeof(key);

}

/*****************************************************************************/

/*

 * set the key for the index entry

 */

static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,

					void *buffer, uint16_t bufmax)

{

	const struct afs_vnode *vnode = cookie_netfs_data;

	struct {

		u32 vnode_id;

		u32 unique;

		u32 vnode_id_ext[2];	/* Allow for a 96-bit key */

	} __packed key;

	_enter("{%x,%x,%llx},%p,%u",

	       vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,

	       buffer, bufmax);

	/* Allow for a 96-bit key */

	memset(&key, 0, sizeof(key));

	key.vnode_id		= vnode->fid.vnode;

	key.unique		= vnode->fid.unique;

	key.vnode_id_ext[0]	= 0;

	key.vnode_id_ext[1]	= 0;

	if (sizeof(key) > bufmax)

		return 0;

	memcpy(buffer, &key, sizeof(key));

	return sizeof(key);

}

/*

 * provide updated file attributes

 */

	*size = vnode->status.size;

}

struct afs_vnode_cache_aux {

	u64 data_version;

} __packed;

/*

 * provide new auxiliary cache data

 */

static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,

					void *buffer, uint16_t bufmax)

{

	const struct afs_vnode *vnode = cookie_netfs_data;

	struct afs_vnode_cache_aux aux;

	_enter("{%x,%x,%Lx},%p,%u",

	       vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,

	       buffer, bufmax);

	aux.data_version = vnode->status.data_version;

	if (bufmax < sizeof(aux))

		return 0;

	memcpy(buffer, &aux, sizeof(aux));

	return sizeof(aux);

}

/*

 * check that the auxiliary data indicates that the entry is still valid

 */

#ifdef CONFIG_AFS_FSCACHE

	cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,

					     &afs_cell_cache_index_def,

					     cell->name, strlen(cell->name),

					     NULL, 0,

					     cell, true);

#endif

	ret = afs_proc_cell_setup(net, cell);

	spin_unlock(&net->proc_cells_lock);

#ifdef CONFIG_AFS_FSCACHE

	fscache_relinquish_cookie(cell->cache, 0);

	fscache_relinquish_cookie(cell->cache, NULL, false);

	cell->cache = NULL;

#endif

	return inode;

}

/*

 * Get a cache cookie for an inode.

 */

static void afs_get_inode_cache(struct afs_vnode *vnode)

{

#ifdef CONFIG_AFS_FSCACHE

	struct {

		u32 vnode_id;

		u32 unique;

		u32 vnode_id_ext[2];	/* Allow for a 96-bit key */

	} __packed key;

	struct afs_vnode_cache_aux aux;

	key.vnode_id		= vnode->fid.vnode;

	key.unique		= vnode->fid.unique;

	key.vnode_id_ext[0]	= 0;

	key.vnode_id_ext[1]	= 0;

	aux.data_version	= vnode->status.data_version;

	vnode->cache = fscache_acquire_cookie(vnode->volume->cache,

					      &afs_vnode_cache_index_def,

					      &key, sizeof(key),

					      &aux, sizeof(aux),

					      vnode, true);

#endif

}

/*

 * inode retrieval

 */

	/* set up caching before mapping the status, as map-status reads the

	 * first page of symlinks to see if they're really mountpoints */

	inode->i_size = vnode->status.size;

#ifdef CONFIG_AFS_FSCACHE

	vnode->cache = fscache_acquire_cookie(vnode->volume->cache,

					      &afs_vnode_cache_index_def,

					      vnode, true);

#endif

	afs_get_inode_cache(vnode);

	ret = afs_inode_map_status(vnode, key);

	if (ret < 0)

	/* failure */

bad_inode:

#ifdef CONFIG_AFS_FSCACHE

	fscache_relinquish_cookie(vnode->cache, ret == -ENOENT);

	fscache_relinquish_cookie(vnode->cache, NULL, ret == -ENOENT);

	vnode->cache = NULL;

#endif

	iget_failed(inode);

	}

#ifdef CONFIG_AFS_FSCACHE

	fscache_relinquish_cookie(vnode->cache,

	{

		struct afs_vnode_cache_aux aux;

		aux.data_version = vnode->status.data_version;

		fscache_relinquish_cookie(vnode->cache, &aux,

					  test_bit(AFS_VNODE_DELETED, &vnode->flags));

		vnode->cache = NULL;

	}

#endif

	afs_put_permits(vnode->permit_cache);