Viewing: xattr_cache.c
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2012 Xyratex Technology Limited
*
* Copyright (c) 2013, 2017, Intel Corporation.
*
* Author: Andrew Perepechko <Andrew_Perepechko@xyratex.com>
*/
#define DEBUG_SUBSYSTEM S_LLITE
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <obd_support.h>
#include <lustre_dlm.h>
#include "llite_internal.h"
/* If we ever have hundreds of extended attributes, we might want to consider
* using a hash or a tree structure instead of list for faster lookups.
*/
struct ll_xattr_entry {
struct list_head xe_list; /* protected by lli_xattrs_list_rwsem */
char *xe_name; /* xattr name, \0-terminated */
char *xe_value; /* xattr value */
unsigned int xe_namelen; /* strlen(xe_name) + 1 */
unsigned int xe_vallen; /* xattr value length */
};
static struct kmem_cache *xattr_kmem;
static struct lu_kmem_descr xattr_caches[] = {
{
.ckd_cache = &xattr_kmem,
.ckd_name = "xattr_kmem",
.ckd_size = sizeof(struct ll_xattr_entry)
},
{
.ckd_cache = NULL
}
};
int ll_xattr_init(void)
{
return lu_kmem_init(xattr_caches);
}
void ll_xattr_fini(void)
{
lu_kmem_fini(xattr_caches);
}
/**
* ll_xattr_cache_init() - Initializes xattr cache for an inode.
*
* This initializes the xattr list and marks cache presence.
*
* @lli: lustre ll_inode_info struct (list of xattrs)
*
* Returns:
* * %void
*/
static void ll_xattr_cache_init(struct ll_inode_info *lli)
{
ENTRY;
LASSERT(lli != NULL);
INIT_LIST_HEAD(&lli->lli_xattrs);
set_bit(LLIF_XATTR_CACHE, &lli->lli_flags);
}
/**
* ll_xattr_cache_find() - This looks for a specific extended attribute.
*
* @cache: Find in this list @xattr_name
* @xattr_name: xattr name to find
* @xattr: Return matched xattr attribute on success
*
* Find in @cache and return @xattr_name attribute in @xattr,
* for the NULL @xattr_name return the first cached @xattr.
*
* Returns:
* * %0 success
* * %-ENODATA if not found
*/
static int ll_xattr_cache_find(struct list_head *cache,
const char *xattr_name,
struct ll_xattr_entry **xattr)
{
struct ll_xattr_entry *entry;
ENTRY;
list_for_each_entry(entry, cache, xe_list) {
/* xattr_name == NULL means look for any entry */
if (xattr_name == NULL ||
strcmp(xattr_name, entry->xe_name) == 0) {
*xattr = entry;
CDEBUG(D_CACHE, "find: [%s]=%.*s\n",
entry->xe_name, entry->xe_vallen,
entry->xe_value);
RETURN(0);
}
}
RETURN(-ENODATA);
}
/**
* ll_xattr_cache_add() - This adds an xattr.
*
* @cache: list of xattr for an inode (struct ll_xattr_entry)
* @xattr_name: name of xattr to be added to the cache list
* @xattr_val: value of xattr to be added to the cache list
* @xattr_val_len: length of xattr value
*
* Add @xattr_name attr with @xattr_val value and @xattr_val_len length,
*
* Returns:
* * %0 success
* * %-ENOMEM if no memory could be allocated for the cached attr
* * %-EPROTO if duplicate xattr is being added
*/
static int ll_xattr_cache_add(struct list_head *cache,
const char *xattr_name,
const char *xattr_val,
unsigned int xattr_val_len)
{
struct ll_xattr_entry *xattr;
ENTRY;
if (ll_xattr_cache_find(cache, xattr_name, &xattr) == 0) {
if (!strcmp(xattr_name, LL_XATTR_NAME_ENCRYPTION_CONTEXT) ||
!strcmp(xattr_name, LL_XATTR_NAME_ENCRYPTION_CONTEXT_OLD))
/* it means enc ctx was already in cache,
* ignore error as it cannot be modified
*/
RETURN(0);
CDEBUG(D_CACHE, "duplicate xattr: [%s]\n", xattr_name);
RETURN(-EPROTO);
}
OBD_SLAB_ALLOC_PTR_GFP(xattr, xattr_kmem, GFP_NOFS);
if (xattr == NULL) {
CDEBUG(D_CACHE, "failed to allocate xattr\n");
RETURN(-ENOMEM);
}
xattr->xe_namelen = strlen(xattr_name) + 1;
OBD_ALLOC(xattr->xe_name, xattr->xe_namelen);
if (!xattr->xe_name) {
CDEBUG(D_CACHE, "failed to alloc xattr name %u\n",
xattr->xe_namelen);
goto err_name;
}
OBD_ALLOC(xattr->xe_value, xattr_val_len);
if (!xattr->xe_value) {
CDEBUG(D_CACHE, "failed to alloc xattr value %d\n",
xattr_val_len);
goto err_value;
}
memcpy(xattr->xe_name, xattr_name, xattr->xe_namelen);
memcpy(xattr->xe_value, xattr_val, xattr_val_len);
xattr->xe_vallen = xattr_val_len;
list_add(&xattr->xe_list, cache);
CDEBUG(D_CACHE, "set: [%s]=%.*s\n", xattr_name,
xattr_val_len, xattr_val);
RETURN(0);
err_value:
OBD_FREE(xattr->xe_name, xattr->xe_namelen);
err_name:
OBD_SLAB_FREE_PTR(xattr, xattr_kmem);
RETURN(-ENOMEM);
}
/**
* ll_xattr_cache_del() - This removes an extended attribute from cache.
*
* @cache: list of xattr for an inode (struct ll_xattr_entry)
* @xattr_name: name of xattr to be deleted to the cache list
*
* Remove @xattr_name attribute from @cache.
*
* Returns:
* * %0 success
* * %-ENODATA if @xattr_name is not cached
*/
static int ll_xattr_cache_del(struct list_head *cache,
const char *xattr_name)
{
struct ll_xattr_entry *xattr;
ENTRY;
CDEBUG(D_CACHE, "del xattr: %s\n", xattr_name);
if (ll_xattr_cache_find(cache, xattr_name, &xattr) == 0) {
list_del(&xattr->xe_list);
OBD_FREE(xattr->xe_name, xattr->xe_namelen);
OBD_FREE(xattr->xe_value, xattr->xe_vallen);
OBD_SLAB_FREE_PTR(xattr, xattr_kmem);
RETURN(0);
}
RETURN(-ENODATA);
}
/**
* ll_xattr_cache_list() - This iterates cached extended attributes.
*
* @cache: list of xattr for an inode (struct ll_xattr_entry)
* @xld_buffer: buffer(space) to store xattrs
* @xld_size: size of @xld_buffer
*
* Walk over cached attributes in @cache and fill in @xld_buffer or only
* calculate buffer size if @xld_buffer is NULL.
*
* Returns:
* * >= 0 buffer list size
* * %-ENODATA if the list cannot fit @xld_size buffer
*/
static int ll_xattr_cache_list(struct list_head *cache,
char *xld_buffer,
int xld_size)
{
struct ll_xattr_entry *xattr, *tmp;
int xld_tail = 0;
ENTRY;
list_for_each_entry_safe(xattr, tmp, cache, xe_list) {
CDEBUG(D_CACHE, "list: buffer=%p[%d] name=%s\n",
xld_buffer, xld_tail, xattr->xe_name);
if (xld_buffer) {
xld_size -= xattr->xe_namelen;
if (xld_size < 0)
break;
memcpy(&xld_buffer[xld_tail],
xattr->xe_name, xattr->xe_namelen);
}
xld_tail += xattr->xe_namelen;
}
if (xld_size < 0)
RETURN(-ERANGE);
RETURN(xld_tail);
}
/**
* ll_xattr_cache_valid() - Check if the xattr cache is initialized.
*
* @lli: lustre ll_inode_info struct (list of xattrs)
*
* Returns:
* * %0 @cache is not initialized
* * %1 @cache is initialized
*/
static int ll_xattr_cache_valid(struct ll_inode_info *lli)
{
return test_bit(LLIF_XATTR_CACHE, &lli->lli_flags);
}
/**
* ll_xattr_cache_filled() - Check if the xattr cache is filled.
*
* @lli: lustre ll_inode_info struct (list of xattrs)
*
* Returns:
* * %0 @cache is not filled
* * %1 @cache is filled
*/
static int ll_xattr_cache_filled(struct ll_inode_info *lli)
{
return test_bit(LLIF_XATTR_CACHE_FILLED, &lli->lli_flags);
}
/**
* ll_xattr_cache_destroy_locked() - This finalizes the xattr cache.
*
* @lli: lustre ll_inode_info struct (list of xattrs)
*
* Free all xattr memory. @lli is the inode info pointer.
*
* Returns:
* * %0 no error occured
*/
static int ll_xattr_cache_destroy_locked(struct ll_inode_info *lli)
{
ENTRY;
if (!ll_xattr_cache_valid(lli))
RETURN(0);
while (ll_xattr_cache_del(&lli->lli_xattrs, NULL) == 0)
; /* empty loop */
clear_bit(LLIF_XATTR_CACHE_FILLED, &lli->lli_flags);
clear_bit(LLIF_XATTR_CACHE, &lli->lli_flags);
RETURN(0);
}
int ll_xattr_cache_destroy(struct inode *inode)
{
struct ll_inode_info *lli = ll_i2info(inode);
int rc;
ENTRY;
down_write(&lli->lli_xattrs_list_rwsem);
rc = ll_xattr_cache_destroy_locked(lli);
up_write(&lli->lli_xattrs_list_rwsem);
RETURN(rc);
}
/*
* ll_xattr_cache_empty - empty xattr cache for @ino
*
* Similar to ll_xattr_cache_destroy(), but preserves encryption context.
* So only LLIF_XATTR_CACHE_FILLED flag is cleared, but not LLIF_XATTR_CACHE.
*/
int ll_xattr_cache_empty(struct inode *inode)
{
struct ll_inode_info *lli = ll_i2info(inode);
struct ll_xattr_entry *entry, *n;
ENTRY;
down_write(&lli->lli_xattrs_list_rwsem);
if (!ll_xattr_cache_valid(lli) ||
!ll_xattr_cache_filled(lli))
GOTO(out_empty, 0);
list_for_each_entry_safe(entry, n, &lli->lli_xattrs, xe_list) {
if (strcmp(entry->xe_name, xattr_for_enc(inode)) == 0)
continue;
CDEBUG(D_CACHE, "delete: %s\n", entry->xe_name);
list_del(&entry->xe_list);
OBD_FREE(entry->xe_name, entry->xe_namelen);
OBD_FREE(entry->xe_value, entry->xe_vallen);
OBD_SLAB_FREE_PTR(entry, xattr_kmem);
}
clear_bit(LLIF_XATTR_CACHE_FILLED, &lli->lli_flags);
out_empty:
up_write(&lli->lli_xattrs_list_rwsem);
RETURN(0);
}
/**
* ll_xattr_find_get_lock() - Match or enqueue a PR lock.
*
* @inode: Whose xattr is being accessed
* @oit: lookup_intent struct (info of lock request)
* @req: ptlrpc_request struct
*
* Find or request an LDLM lock with xattr data.
* Since LDLM does not provide API for atomic match_or_enqueue,
* the function handles it with a separate enq lock.
* If successful, the function exits with a write lock held
* on lli_xattrs_list_rwsem.
*
* Returns:
* * %0 no error occured
* * %-ENOMEM not enough memory
*/
static int ll_xattr_find_get_lock(struct inode *inode,
struct lookup_intent *oit,
struct ptlrpc_request **req)
{
enum ldlm_mode mode;
struct lustre_handle lockh = { 0 };
struct md_op_data *op_data;
struct ll_inode_info *lli = ll_i2info(inode);
struct ll_sb_info *sbi = ll_i2sbi(inode);
struct obd_export *exp = sbi->ll_md_exp;
int rc;
ENTRY;
mutex_lock(&lli->lli_xattrs_enq_lock);
/* inode may have been shrunk and recreated, so data is gone, match lock
* only when data exists.
*/
if (ll_xattr_cache_filled(lli)) {
/* Try matching first. */
mode = ll_take_md_lock(inode, MDS_INODELOCK_XATTR, &lockh, 0,
LCK_PR);
if (mode != 0) {
/* fake oit in mdc_revalidate_lock() manner */
oit->it_lock_handle = lockh.cookie;
oit->it_lock_mode = mode;
goto out;
}
}
/* Enqueue if the lock isn't cached locally. */
op_data = ll_prep_md_op_data(NULL, inode, NULL, NULL, 0, 0,
LUSTRE_OPC_ANY, NULL);
if (IS_ERR(op_data)) {
mutex_unlock(&lli->lli_xattrs_enq_lock);
RETURN(PTR_ERR(op_data));
}
op_data->op_valid = OBD_MD_FLXATTR | OBD_MD_FLXATTRLS;
rc = ll_intent_lock(exp, op_data, oit, req,
&ll_md_blocking_ast, 0, true);
ll_finish_md_op_data(op_data);
*req = oit->it_request;
if (rc < 0) {
CDEBUG(D_CACHE,
"md_intent_lock failed with %d for fid "DFID"\n", rc,
PFID(ll_inode2fid(inode)));
mutex_unlock(&lli->lli_xattrs_enq_lock);
RETURN(rc);
}
out:
down_write(&lli->lli_xattrs_list_rwsem);
mutex_unlock(&lli->lli_xattrs_enq_lock);
RETURN(0);
}
/**
* ll_xattr_cache_refill() - Refill the xattr cache.
*
* @inode: Whose xattr is being accessed
*
* Fetch and cache the whole of xattrs for @inode, thanks to the write lock
* on lli_xattrs_list_rwsem obtained from ll_xattr_find_get_lock().
* If successful, this write lock is kept.
*
* Returns:
* * %0 no error occured
* * %-EPROTO network protocol error
* * %-ENOMEM not enough memory for the cache
*/
static int ll_xattr_cache_refill(struct inode *inode)
{
struct lookup_intent oit = { .it_op = IT_GETXATTR };
struct ll_sb_info *sbi = ll_i2sbi(inode);
struct ptlrpc_request *req = NULL;
const char *xdata, *xval, *xtail, *xvtail;
struct ll_inode_info *lli = ll_i2info(inode);
struct mdt_body *body;
__u32 *xsizes;
int rc = 0, i;
ENTRY;
CFS_FAIL_TIMEOUT(OBD_FAIL_LLITE_XATTR_PAUSE, cfs_fail_val ?: 2);
rc = ll_xattr_find_get_lock(inode, &oit, &req);
if (rc)
GOTO(err_req, rc);
/* Do we have the data at this point? */
if (ll_xattr_cache_filled(lli)) {
ll_stats_ops_tally(sbi, LPROC_LL_GETXATTR_HITS, 1);
ll_intent_drop_lock(&oit);
GOTO(err_req, rc = 0);
}
/* Matched but no cache? Cancelled on error by a parallel refill. */
if (unlikely(req == NULL)) {
CDEBUG(D_CACHE, "cancelled by a parallel getxattr\n");
ll_intent_drop_lock(&oit);
GOTO(err_unlock, rc = -EAGAIN);
}
body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
if (body == NULL) {
CERROR("no MDT BODY in the refill xattr reply\n");
GOTO(err_cancel, rc = -EPROTO);
}
/* do not need swab xattr data */
xdata = req_capsule_server_sized_get(&req->rq_pill, &RMF_EADATA,
body->mbo_eadatasize);
xval = req_capsule_server_sized_get(&req->rq_pill, &RMF_EAVALS,
body->mbo_aclsize);
xsizes = req_capsule_server_sized_get(&req->rq_pill, &RMF_EAVALS_LENS,
body->mbo_max_mdsize *
sizeof(__u32));
if (xdata == NULL || xval == NULL || xsizes == NULL) {
CERROR("wrong setxattr reply\n");
GOTO(err_cancel, rc = -EPROTO);
}
xtail = xdata + body->mbo_eadatasize;
xvtail = xval + body->mbo_aclsize;
CDEBUG(D_CACHE, "caching: xdata=%p xtail=%p\n", xdata, xtail);
if (!ll_xattr_cache_valid(lli))
ll_xattr_cache_init(lli);
for (i = 0; i < body->mbo_max_mdsize; i++) {
CDEBUG(D_CACHE, "caching [%s]=%.*s\n", xdata, *xsizes, xval);
/* Perform consistency checks: attr names and vals in pill */
if (memchr(xdata, 0, xtail - xdata) == NULL) {
CERROR("xattr protocol violation (names are broken)\n");
rc = -EPROTO;
} else if (xval + *xsizes > xvtail) {
CERROR("xattr protocol violation (vals are broken)\n");
rc = -EPROTO;
} else if (CFS_FAIL_CHECK(OBD_FAIL_LLITE_XATTR_ENOMEM)) {
rc = -ENOMEM;
} else if (!strcmp(xdata, XATTR_NAME_ACL_ACCESS)) {
/* Filter out ACL ACCESS since it's cached separately */
CDEBUG(D_CACHE, "not caching %s\n",
XATTR_NAME_ACL_ACCESS);
rc = 0;
} else if (ll_xattr_is_seclabel(xdata)) {
/* Filter out security label, it is cached in slab */
CDEBUG(D_CACHE, "not caching %s\n", xdata);
rc = 0;
} else if (!strcmp(xdata, XATTR_NAME_SOM)) {
/* Filter out trusted.som, it is not cached on client */
CDEBUG(D_CACHE, "not caching trusted.som\n");
rc = 0;
} else {
rc = ll_xattr_cache_add(&lli->lli_xattrs, xdata, xval,
*xsizes);
}
if (rc < 0) {
ll_xattr_cache_destroy_locked(lli);
GOTO(err_cancel, rc);
}
xdata += strlen(xdata) + 1;
xval += *xsizes;
xsizes++;
}
if (xdata != xtail || xval != xvtail)
CERROR("a hole in xattr data\n");
else
set_bit(LLIF_XATTR_CACHE_FILLED, &lli->lli_flags);
ll_set_lock_data(sbi->ll_md_exp, inode, &oit, NULL);
ll_intent_drop_lock(&oit);
ptlrpc_req_put(req);
RETURN(0);
err_cancel:
ldlm_lock_decref_and_cancel((struct lustre_handle *)
&oit.it_lock_handle,
oit.it_lock_mode);
err_unlock:
up_write(&lli->lli_xattrs_list_rwsem);
err_req:
if (rc == -ERANGE)
rc = -EAGAIN;
ptlrpc_req_put(req);
RETURN(rc);
}
/**
* ll_xattr_cache_get() - Get an xattr value or list xattrs using the
* write-through cache.
*
* @inode: Whose xattr is being accessed
* @name: name of xattr to be get
* @buffer: buffer(space) to store xattrs
* @size: size of the @buffer
* @valid: Operations to be performed
*
* Get the xattr value (@valid has OBD_MD_FLXATTR set) of @name or
* list xattr names (@valid has OBD_MD_FLXATTRLS set) for @inode.
* The resulting value/list is stored in @buffer if the former
* is not larger than @size.
*
* Returns:
* * %0 no error occured
* * %-EPROTO network protocol error
* * %-ENOMEM not enough memory for the cache
* * %-ERANGE the buffer is not large enough
* * %-ENODATA no such attr or the list is empty
*/
int ll_xattr_cache_get(struct inode *inode,
const char *name,
char *buffer,
size_t size,
__u64 valid)
{
struct ll_inode_info *lli = ll_i2info(inode);
int rc = 0;
ENTRY;
LASSERT(!!(valid & OBD_MD_FLXATTR) ^ !!(valid & OBD_MD_FLXATTRLS));
down_read(&lli->lli_xattrs_list_rwsem);
/* For performance reasons, we do not want to refill complete xattr
* cache if we are just interested in encryption context.
*/
if ((valid & OBD_MD_FLXATTRLS ||
strcmp(name, xattr_for_enc(inode)) != 0) &&
!ll_xattr_cache_filled(lli)) {
up_read(&lli->lli_xattrs_list_rwsem);
rc = ll_xattr_cache_refill(inode);
if (rc)
RETURN(rc);
/* Turn the write lock obtained in ll_xattr_cache_refill()
* into a read lock.
*/
downgrade_write(&lli->lli_xattrs_list_rwsem);
} else {
ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_GETXATTR_HITS, 1);
}
if (!ll_xattr_cache_valid(lli))
GOTO(out, rc = -ENODATA);
if (valid & OBD_MD_FLXATTR) {
struct ll_xattr_entry *xattr;
rc = ll_xattr_cache_find(&lli->lli_xattrs, name, &xattr);
if (rc == 0) {
rc = xattr->xe_vallen;
/* zero size means we are only requested size in rc */
if (size != 0) {
if (size >= xattr->xe_vallen)
memcpy(buffer, xattr->xe_value,
xattr->xe_vallen);
else
rc = -ERANGE;
}
/* Return the project id when the virtual project id xattr
* is explicitly asked.
*/
} else if (strcmp(name, XATTR_NAME_PROJID) == 0) {
/* 10 chars to hold u32 in decimal, plus ending \0 */
char projid[11];
rc = snprintf(projid, sizeof(projid),
"%u", lli->lli_projid);
if (size != 0) {
if (rc <= size)
memcpy(buffer, projid, rc);
else
rc = -ERANGE;
}
}
} else if (valid & OBD_MD_FLXATTRLS) {
rc = ll_xattr_cache_list(&lli->lli_xattrs,
size ? buffer : NULL, size);
}
GOTO(out, rc);
out:
up_read(&lli->lli_xattrs_list_rwsem);
RETURN(rc);
}
/**
* ll_xattr_cache_insert() - Insert an xattr value into the cache.
*
* @inode: Whose xattr is being accessed
* @name: xattr name to be inserted
* @buffer: value to be inserted
* @size: size of the @buffer
*
* Add @name xattr with @buffer value and @size length for @inode.
* Init cache for @inode if necessary.
*
* Returns:
* * %0 success
* * <0 from ll_xattr_cache_add(), except -EPROTO is ignored for
* LL_XATTR_NAME_ENCRYPTION_CONTEXT xattr
*/
int ll_xattr_cache_insert(struct inode *inode,
const char *name,
char *buffer,
size_t size)
{
struct ll_inode_info *lli = ll_i2info(inode);
int rc;
ENTRY;
down_write(&lli->lli_xattrs_list_rwsem);
if (!ll_xattr_cache_valid(lli))
ll_xattr_cache_init(lli);
rc = ll_xattr_cache_add(&lli->lli_xattrs, name, buffer, size);
up_write(&lli->lli_xattrs_list_rwsem);
RETURN(rc);
}
