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-rw-r--r--fs/kernfs/file.c45
-rw-r--r--fs/sysfs/file.c31
-rw-r--r--include/linux/kernfs.h8
-rw-r--r--include/linux/sysfs.h9
4 files changed, 71 insertions, 22 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 4429d6d9217f..70186e2e692a 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -106,7 +106,7 @@ static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
const struct kernfs_ops *ops;
/*
- * @of->mutex nests outside active ref and is just to ensure that
+ * @of->mutex nests outside active ref and is primarily to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
@@ -194,7 +194,7 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
return -ENOMEM;
/*
- * @of->mutex nests outside active ref and is just to ensure that
+ * @of->mutex nests outside active ref and is primarily to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
@@ -278,19 +278,16 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
len = min_t(size_t, count, PAGE_SIZE);
}
- buf = kmalloc(len + 1, GFP_KERNEL);
+ buf = of->prealloc_buf;
+ if (!buf)
+ buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
- if (copy_from_user(buf, user_buf, len)) {
- len = -EFAULT;
- goto out_free;
- }
- buf[len] = '\0'; /* guarantee string termination */
-
/*
- * @of->mutex nests outside active ref and is just to ensure that
- * the ops aren't called concurrently for the same open file.
+ * @of->mutex nests outside active ref and is used both to ensure that
+ * the ops aren't called concurrently for the same open file, and
+ * to provide exclusive access to ->prealloc_buf (when that exists).
*/
mutex_lock(&of->mutex);
if (!kernfs_get_active(of->kn)) {
@@ -299,19 +296,27 @@ static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf,
goto out_free;
}
+ if (copy_from_user(buf, user_buf, len)) {
+ len = -EFAULT;
+ goto out_unlock;
+ }
+ buf[len] = '\0'; /* guarantee string termination */
+
ops = kernfs_ops(of->kn);
if (ops->write)
len = ops->write(of, buf, len, *ppos);
else
len = -EINVAL;
- kernfs_put_active(of->kn);
- mutex_unlock(&of->mutex);
-
if (len > 0)
*ppos += len;
+
+out_unlock:
+ kernfs_put_active(of->kn);
+ mutex_unlock(&of->mutex);
out_free:
- kfree(buf);
+ if (buf != of->prealloc_buf)
+ kfree(buf);
return len;
}
@@ -685,6 +690,14 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
*/
of->atomic_write_len = ops->atomic_write_len;
+ if (ops->prealloc) {
+ int len = of->atomic_write_len ?: PAGE_SIZE;
+ of->prealloc_buf = kmalloc(len + 1, GFP_KERNEL);
+ error = -ENOMEM;
+ if (!of->prealloc_buf)
+ goto err_free;
+ }
+
/*
* Always instantiate seq_file even if read access doesn't use
* seq_file or is not requested. This unifies private data access
@@ -715,6 +728,7 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
err_close:
seq_release(inode, file);
err_free:
+ kfree(of->prealloc_buf);
kfree(of);
err_out:
kernfs_put_active(kn);
@@ -728,6 +742,7 @@ static int kernfs_fop_release(struct inode *inode, struct file *filp)
kernfs_put_open_node(kn, of);
seq_release(inode, filp);
+ kfree(of->prealloc_buf);
kfree(of);
return 0;
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 589abee16a39..4ad3721a991c 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -184,6 +184,17 @@ static const struct kernfs_ops sysfs_file_kfops_rw = {
.write = sysfs_kf_write,
};
+static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
+ .write = sysfs_kf_write,
+ .prealloc = true,
+};
+
+static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
+ .seq_show = sysfs_kf_seq_show,
+ .write = sysfs_kf_write,
+ .prealloc = true,
+};
+
static const struct kernfs_ops sysfs_bin_kfops_ro = {
.read = sysfs_kf_bin_read,
};
@@ -222,13 +233,19 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent,
kobject_name(kobj)))
return -EINVAL;
- if (sysfs_ops->show && sysfs_ops->store)
- ops = &sysfs_file_kfops_rw;
- else if (sysfs_ops->show)
+ if (sysfs_ops->show && sysfs_ops->store) {
+ if (mode & SYSFS_PREALLOC)
+ ops = &sysfs_prealloc_kfops_rw;
+ else
+ ops = &sysfs_file_kfops_rw;
+ } else if (sysfs_ops->show)
ops = &sysfs_file_kfops_ro;
- else if (sysfs_ops->store)
- ops = &sysfs_file_kfops_wo;
- else
+ else if (sysfs_ops->store) {
+ if (mode & SYSFS_PREALLOC)
+ ops = &sysfs_prealloc_kfops_wo;
+ else
+ ops = &sysfs_file_kfops_wo;
+ } else
ops = &sysfs_file_kfops_empty;
size = PAGE_SIZE;
@@ -253,7 +270,7 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent,
if (!attr->ignore_lockdep)
key = attr->key ?: (struct lock_class_key *)&attr->skey;
#endif
- kn = __kernfs_create_file(parent, attr->name, mode, size, ops,
+ kn = __kernfs_create_file(parent, attr->name, mode & 0777, size, ops,
(void *)attr, ns, true, key);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 30faf797c2c3..d4e01b358341 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -179,6 +179,7 @@ struct kernfs_open_file {
struct mutex mutex;
int event;
struct list_head list;
+ char *prealloc_buf;
size_t atomic_write_len;
bool mmapped;
@@ -214,6 +215,13 @@ struct kernfs_ops {
* larger ones are rejected with -E2BIG.
*/
size_t atomic_write_len;
+ /*
+ * "prealloc" causes a buffer to be allocated at open for
+ * all read/write requests. As ->seq_show uses seq_read()
+ * which does its own allocation, it is incompatible with
+ * ->prealloc. Provide ->read and ->write with ->prealloc.
+ */
+ bool prealloc;
ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
loff_t off);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index f97d0dbb59fa..ddad16148bd6 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -70,6 +70,8 @@ struct attribute_group {
* for examples..
*/
+#define SYSFS_PREALLOC 010000
+
#define __ATTR(_name, _mode, _show, _store) { \
.attr = {.name = __stringify(_name), \
.mode = VERIFY_OCTAL_PERMISSIONS(_mode) }, \
@@ -77,6 +79,13 @@ struct attribute_group {
.store = _store, \
}
+#define __ATTR_PREALLOC(_name, _mode, _show, _store) { \
+ .attr = {.name = __stringify(_name), \
+ .mode = SYSFS_PREALLOC | VERIFY_OCTAL_PERMISSIONS(_mode) },\
+ .show = _show, \
+ .store = _store, \
+}
+
#define __ATTR_RO(_name) { \
.attr = { .name = __stringify(_name), .mode = S_IRUGO }, \
.show = _name##_show, \