[RFC 18/19] cachefiles: support on demand read
Jeffle Xu
jefflexu at linux.alibaba.com
Fri Dec 10 18:36:18 AEDT 2021
fs can call cachefiles_demand_read() helper function to enqueue read
request for demand reading.
Signed-off-by: Jeffle Xu <jefflexu at linux.alibaba.com>
---
fs/cachefiles/daemon.c | 148 +++++++++++++++++++++++++++------------
fs/cachefiles/internal.h | 16 +++++
fs/cachefiles/io.c | 56 +++++++++++++++
3 files changed, 175 insertions(+), 45 deletions(-)
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 951963e72b44..7d174a39cd1c 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -44,6 +44,7 @@ static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
static int cachefiles_daemon_mode(struct cachefiles_cache *, char *);
static int cachefiles_daemon_bind(struct cachefiles_cache *, char *);
static void cachefiles_daemon_unbind(struct cachefiles_cache *);
+static int cachefiles_daemon_done(struct cachefiles_cache *, char *);
static unsigned long cachefiles_open;
@@ -77,6 +78,7 @@ static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
{ "secctx", cachefiles_daemon_secctx },
{ "tag", cachefiles_daemon_tag },
{ "mode", cachefiles_daemon_mode },
+ { "done", cachefiles_daemon_done },
{ "", NULL }
};
@@ -110,6 +112,8 @@ static int cachefiles_daemon_open(struct inode *inode, struct file *file)
INIT_LIST_HEAD(&cache->volumes);
INIT_LIST_HEAD(&cache->object_list);
spin_lock_init(&cache->object_list_lock);
+ idr_init(&cache->reqs);
+ spin_lock_init(&cache->reqs_lock);
/* set default caching limits
* - limit at 1% free space and/or free files
@@ -144,6 +148,7 @@ static int cachefiles_daemon_release(struct inode *inode, struct file *file)
cachefiles_daemon_unbind(cache);
/* clean up the control file interface */
+ idr_destroy(&cache->reqs);
cache->cachefilesd = NULL;
file->private_data = NULL;
cachefiles_open = 0;
@@ -164,6 +169,7 @@ static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
unsigned long long b_released;
unsigned f_released;
char buffer[256];
+ void *buf;
int n;
//_enter(",,%zu,", buflen);
@@ -171,38 +177,53 @@ static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
if (!test_bit(CACHEFILES_READY, &cache->flags))
return 0;
- /* check how much space the cache has */
- cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
-
- /* summarise */
- f_released = atomic_xchg(&cache->f_released, 0);
- b_released = atomic_long_xchg(&cache->b_released, 0);
- clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
-
- n = snprintf(buffer, sizeof(buffer),
- "cull=%c"
- " frun=%llx"
- " fcull=%llx"
- " fstop=%llx"
- " brun=%llx"
- " bcull=%llx"
- " bstop=%llx"
- " freleased=%x"
- " breleased=%llx",
- test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
- (unsigned long long) cache->frun,
- (unsigned long long) cache->fcull,
- (unsigned long long) cache->fstop,
- (unsigned long long) cache->brun,
- (unsigned long long) cache->bcull,
- (unsigned long long) cache->bstop,
- f_released,
- b_released);
+ if (cache->mode == CACHEFILES_MODE_CACHE) {
+ /* check how much space the cache has */
+ cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
+
+ /* summarise */
+ f_released = atomic_xchg(&cache->f_released, 0);
+ b_released = atomic_long_xchg(&cache->b_released, 0);
+ clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
+
+ n = snprintf(buffer, sizeof(buffer),
+ "cull=%c"
+ " frun=%llx"
+ " fcull=%llx"
+ " fstop=%llx"
+ " brun=%llx"
+ " bcull=%llx"
+ " bstop=%llx"
+ " freleased=%x"
+ " breleased=%llx",
+ test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
+ (unsigned long long) cache->frun,
+ (unsigned long long) cache->fcull,
+ (unsigned long long) cache->fstop,
+ (unsigned long long) cache->brun,
+ (unsigned long long) cache->bcull,
+ (unsigned long long) cache->bstop,
+ f_released,
+ b_released);
+ buf = buffer;
+ } else {
+ struct cachefiles_req *req;
+ int id = 0;
+
+ spin_lock(&cache->reqs_lock);
+ req = idr_get_next(&cache->reqs, &id);
+ spin_unlock(&cache->reqs_lock);
+ if (!req)
+ return 0;
+
+ buf = &req->req_in;
+ n = sizeof(req->req_in);
+ }
if (n > buflen)
return -EMSGSIZE;
- if (copy_to_user(_buffer, buffer, n) != 0)
+ if (copy_to_user(_buffer, buf, n) != 0)
return -EFAULT;
return n;
@@ -291,7 +312,7 @@ static ssize_t cachefiles_daemon_write(struct file *file,
* - use EPOLLOUT to indicate culling state
*/
static __poll_t cachefiles_daemon_poll(struct file *file,
- struct poll_table_struct *poll)
+ struct poll_table_struct *poll)
{
struct cachefiles_cache *cache = file->private_data;
__poll_t mask;
@@ -299,11 +320,16 @@ static __poll_t cachefiles_daemon_poll(struct file *file,
poll_wait(file, &cache->daemon_pollwq, poll);
mask = 0;
- if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
- mask |= EPOLLIN;
+ if (cache->mode == CACHEFILES_MODE_CACHE) {
+ if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
+ mask |= EPOLLIN;
- if (test_bit(CACHEFILES_CULLING, &cache->flags))
- mask |= EPOLLOUT;
+ if (test_bit(CACHEFILES_CULLING, &cache->flags))
+ mask |= EPOLLOUT;
+ } else {
+ if(!idr_is_empty(&cache->reqs))
+ mask |= EPOLLIN;
+ }
return mask;
}
@@ -313,7 +339,7 @@ static __poll_t cachefiles_daemon_poll(struct file *file,
* - can be tail-called
*/
static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
- char *args)
+ char *args)
{
pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
@@ -546,6 +572,38 @@ static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
return 0;
}
+/*
+ * Request completion
+ * - command: "done <id>"
+ */
+static int cachefiles_daemon_done(struct cachefiles_cache *cache, char *args)
+{
+ unsigned long id;
+ int ret;
+ struct cachefiles_req *req;
+
+ _enter(",%s", args);
+
+ if (!*args) {
+ pr_err("Empty id specified\n");
+ return -EINVAL;
+ }
+
+ ret = kstrtoul(args, 0, &id);
+ if (ret)
+ return ret;
+
+ spin_lock(&cache->reqs_lock);
+ req = idr_remove(&cache->reqs, id);
+ spin_unlock(&cache->reqs_lock);
+ if (!req)
+ return -EINVAL;
+
+ complete(&req->done);
+
+ return 0;
+}
+
/*
* Request a node in the cache be culled from the current working directory
* - command: "cull <name>"
@@ -704,22 +762,22 @@ static int cachefiles_daemon_mode(struct cachefiles_cache *cache, char *args)
static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
{
_enter("{%u,%u,%u,%u,%u,%u},%s",
- cache->frun_percent,
- cache->fcull_percent,
- cache->fstop_percent,
- cache->brun_percent,
- cache->bcull_percent,
- cache->bstop_percent,
- args);
+ cache->frun_percent,
+ cache->fcull_percent,
+ cache->fstop_percent,
+ cache->brun_percent,
+ cache->bcull_percent,
+ cache->bstop_percent,
+ args);
if (cache->fstop_percent >= cache->fcull_percent ||
- cache->fcull_percent >= cache->frun_percent ||
- cache->frun_percent >= 100)
+ cache->fcull_percent >= cache->frun_percent ||
+ cache->frun_percent >= 100)
return -ERANGE;
if (cache->bstop_percent >= cache->bcull_percent ||
- cache->bcull_percent >= cache->brun_percent ||
- cache->brun_percent >= 100)
+ cache->bcull_percent >= cache->brun_percent ||
+ cache->brun_percent >= 100)
return -ERANGE;
if (*args) {
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 1366e4319b4e..72e6e8744788 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -15,6 +15,7 @@
#include <linux/fscache-cache.h>
#include <linux/cred.h>
#include <linux/security.h>
+#include <linux/idr.h>
#define CACHEFILES_DIO_BLOCK_SIZE 4096
@@ -65,6 +66,18 @@ enum cachefiles_mode {
CACHEFILES_MODE_DEMAND, /* demand read for read-only fs */
};
+struct cachefiles_req_in {
+ uint64_t id;
+ uint64_t off;
+ uint64_t len;
+ char path[NAME_MAX];
+};
+
+struct cachefiles_req {
+ struct completion done;
+ struct cachefiles_req_in req_in;
+};
+
/*
* Cache files cache definition
*/
@@ -107,6 +120,9 @@ struct cachefiles_cache {
char *rootdirname; /* name of cache root directory */
char *secctx; /* LSM security context */
char *tag; /* cache binding tag */
+
+ struct idr reqs;
+ spinlock_t reqs_lock;
};
#include <trace/events/cachefiles.h>
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 95e9107dc3bb..b4f6187f4022 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -540,12 +540,68 @@ static void cachefiles_end_operation(struct netfs_cache_resources *cres)
fscache_end_cookie_access(fscache_cres_cookie(cres), fscache_access_io_end);
}
+static struct cachefiles_req *cachefiles_alloc_req(struct cachefiles_object *object,
+ loff_t start_pos,
+ size_t len)
+{
+ struct cachefiles_req *req;
+ struct cachefiles_req_in *req_in;
+
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+ if (!req)
+ return NULL;
+
+ req_in = &req->req_in;
+
+ req_in->off = start_pos;
+ req_in->len = len;
+ strncpy(req_in->path, object->d_name, sizeof(req_in->path));
+
+ init_completion(&req->done);
+
+ return req;
+}
+
+int cachefiles_demand_read(struct netfs_cache_resources *cres,
+ loff_t start_pos, size_t len)
+{
+ struct cachefiles_object *object;
+ struct cachefiles_cache *cache;
+ struct cachefiles_req *req;
+ int ret;
+
+ object = cachefiles_cres_object(cres);
+ cache = object->volume->cache;
+
+ req = cachefiles_alloc_req(object, start_pos, len);
+ if (!req)
+ return -ENOMEM;
+
+ spin_lock(&cache->reqs_lock);
+ ret = idr_alloc(&cache->reqs, req, 0, 0, GFP_KERNEL);
+ if (ret >= 0)
+ req->req_in.id = ret;
+ spin_unlock(&cache->reqs_lock);
+ if (ret < 0) {
+ kfree(req);
+ return -ENOMEM;
+ }
+
+ wake_up_all(&cache->daemon_pollwq);
+
+ wait_for_completion(&req->done);
+ kfree(req);
+
+ return 0;
+}
+
static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
.end_operation = cachefiles_end_operation,
.read = cachefiles_read,
.write = cachefiles_write,
.prepare_read = cachefiles_prepare_read,
.prepare_write = cachefiles_prepare_write,
+ .demand_read = cachefiles_demand_read,
};
/*
--
2.27.0
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