From ff4dd081977da56566a848f071aed8fa92d604a1 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 30 Aug 2019 11:30:03 -0400
Subject: [PATCH] configfs: stash the data we need into configfs_buffer at open
time
Git-commit: ff4dd081977da56566a848f071aed8fa92d604a1
Patch-mainline: v5.3-rc8
References: git-fixes
simplifies the ->read()/->write()/->release() instances nicely
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/configfs/file.c | 229 +++++++++++++++++++--------------------------
1 file changed, 95 insertions(+), 134 deletions(-)
diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 61e4db4390a1..eee6281a7b35 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -39,24 +39,18 @@ struct configfs_buffer {
bool write_in_progress;
char *bin_buffer;
int bin_buffer_size;
+ int cb_max_size;
+ struct config_item *item;
+ struct module *owner;
+ union {
+ struct configfs_attribute *attr;
+ struct configfs_bin_attribute *bin_attr;
+ };
};
-/**
- * fill_read_buffer - allocate and fill buffer from item.
- * @dentry: dentry pointer.
- * @buffer: data buffer for file.
- *
- * Allocate @buffer->page, if it hasn't been already, then call the
- * config_item's show() method to fill the buffer with this attribute's
- * data.
- * This is called only once, on the file's first read.
- */
-static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
+static int fill_read_buffer(struct configfs_buffer * buffer)
{
- struct configfs_attribute * attr = to_attr(dentry);
- struct config_item * item = to_item(dentry->d_parent);
- int ret = 0;
ssize_t count;
if (!buffer->page)
@@ -64,15 +58,15 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf
if (!buffer->page)
return -ENOMEM;
- count = attr->show(item, buffer->page);
+ count = buffer->attr->show(buffer->item, buffer->page);
+ if (count < 0)
+ return count;
+ if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))
+ return -EIO;
- BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
- if (count >= 0) {
- buffer->needs_read_fill = 0;
- buffer->count = count;
- } else
- ret = count;
- return ret;
+ buffer->needs_read_fill = 0;
+ buffer->count = count;
+ return 0;
}
/**
@@ -97,12 +91,13 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf
static ssize_t
configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
- struct configfs_buffer * buffer = file->private_data;
+ struct configfs_buffer *buffer = file->private_data;
ssize_t retval = 0;
mutex_lock(&buffer->mutex);
if (buffer->needs_read_fill) {
- if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
+ retval = fill_read_buffer(buffer);
+ if (retval)
goto out;
}
pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
@@ -139,9 +134,6 @@ configfs_read_bin_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
struct configfs_buffer *buffer = file->private_data;
- struct dentry *dentry = file->f_path.dentry;
- struct config_item *item = to_item(dentry->d_parent);
- struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
ssize_t retval = 0;
ssize_t len = min_t(size_t, count, PAGE_SIZE);
@@ -156,14 +148,14 @@ configfs_read_bin_file(struct file *file, char __user *buf,
if (buffer->needs_read_fill) {
/* perform first read with buf == NULL to get extent */
- len = bin_attr->read(item, NULL, 0);
+ len = buffer->bin_attr->read(buffer->item, NULL, 0);
if (len <= 0) {
retval = len;
goto out;
}
/* do not exceed the maximum value */
- if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
+ if (buffer->cb_max_size && len > buffer->cb_max_size) {
retval = -EFBIG;
goto out;
}
@@ -176,7 +168,8 @@ configfs_read_bin_file(struct file *file, char __user *buf,
buffer->bin_buffer_size = len;
/* perform second read to fill buffer */
- len = bin_attr->read(item, buffer->bin_buffer, len);
+ len = buffer->bin_attr->read(buffer->item,
+ buffer->bin_buffer, len);
if (len < 0) {
retval = len;
vfree(buffer->bin_buffer);
@@ -226,25 +219,10 @@ fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size
return error ? -EFAULT : count;
}
-
-/**
- * flush_write_buffer - push buffer to config_item.
- * @dentry: dentry to the attribute
- * @buffer: data buffer for file.
- * @count: number of bytes
- *
- * Get the correct pointers for the config_item and the attribute we're
- * dealing with, then call the store() method for the attribute,
- * passing the buffer that we acquired in fill_write_buffer().
- */
-
static int
-flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
+flush_write_buffer(struct configfs_buffer *buffer, size_t count)
{
- struct configfs_attribute * attr = to_attr(dentry);
- struct config_item * item = to_item(dentry->d_parent);
-
- return attr->store(item, buffer->page, count);
+ return buffer->attr->store(buffer->item, buffer->page, count);
}
@@ -268,13 +246,13 @@ flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size
static ssize_t
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
- struct configfs_buffer * buffer = file->private_data;
+ struct configfs_buffer *buffer = file->private_data;
ssize_t len;
mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, buf, count);
if (len > 0)
- len = flush_write_buffer(file->f_path.dentry, buffer, len);
+ len = flush_write_buffer(buffer, len);
if (len > 0)
*ppos += len;
mutex_unlock(&buffer->mutex);
@@ -299,8 +277,6 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct configfs_buffer *buffer = file->private_data;
- struct dentry *dentry = file->f_path.dentry;
- struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
void *tbuf = NULL;
ssize_t len;
@@ -316,8 +292,8 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
/* buffer grows? */
if (*ppos + count > buffer->bin_buffer_size) {
- if (bin_attr->cb_max_size &&
- *ppos + count > bin_attr->cb_max_size) {
+ if (buffer->cb_max_size &&
+ *ppos + count > buffer->cb_max_size) {
len = -EFBIG;
goto out;
}
@@ -349,31 +325,45 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
return len;
}
-static int check_perm(struct inode * inode, struct file * file, int type)
+static int __configfs_open_file(struct inode *inode, struct file *file, int type)
{
- struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
- struct configfs_attribute * attr = to_attr(file->f_path.dentry);
- struct configfs_bin_attribute *bin_attr = NULL;
- struct configfs_buffer * buffer;
- struct configfs_item_operations * ops = NULL;
- int error = 0;
+ struct dentry *dentry = file->f_path.dentry;
+ struct configfs_attribute *attr;
+ struct configfs_buffer *buffer;
+ int error;
- if (!item || !attr)
- goto Einval;
+ error = -ENOMEM;
+ buffer = kzalloc(sizeof(struct configfs_buffer), GFP_KERNEL);
+ if (!buffer)
+ goto out;
- if (type & CONFIGFS_ITEM_BIN_ATTR)
- bin_attr = to_bin_attr(file->f_path.dentry);
+ error = -EINVAL;
+ buffer->item = configfs_get_config_item(dentry->d_parent);
+ if (!buffer->item)
+ goto out_free_buffer;
+
+ attr = to_attr(dentry);
+ if (!attr)
+ goto out_put_item;
+
+ if (type & CONFIGFS_ITEM_BIN_ATTR) {
+ buffer->bin_attr = to_bin_attr(dentry);
+ buffer->cb_max_size = buffer->bin_attr->cb_max_size;
+ } else {
+ buffer->attr = attr;
+ }
+ buffer->owner = attr->ca_owner;
/* Grab the module reference for this attribute if we have one */
- if (!try_module_get(attr->ca_owner)) {
- error = -ENODEV;
- goto Done;
- }
+ error = -ENODEV;
+ if (!try_module_get(buffer->owner))
+ goto out_put_item;
- if (item->ci_type)
- ops = item->ci_type->ct_item_ops;
- else
- goto Eaccess;
+ error = -EACCES;
+ if (!buffer->item->ci_type)
+ goto out_put_module;
+
+ buffer->ops = buffer->item->ci_type->ct_item_ops;
/* File needs write support.
* The inode's perms must say it's ok,
@@ -381,13 +371,11 @@ static int check_perm(struct inode * inode, struct file * file, int type)
*/
if (file->f_mode & FMODE_WRITE) {
if (!(inode->i_mode & S_IWUGO))
- goto Eaccess;
-
+ goto out_put_module;
if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
- goto Eaccess;
-
- if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
- goto Eaccess;
+ goto out_put_module;
+ if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write)
+ goto out_put_module;
}
/* File needs read support.
@@ -396,90 +384,65 @@ static int check_perm(struct inode * inode, struct file * file, int type)
*/
if (file->f_mode & FMODE_READ) {
if (!(inode->i_mode & S_IRUGO))
- goto Eaccess;
-
+ goto out_put_module;
if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
- goto Eaccess;
-
- if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
- goto Eaccess;
+ goto out_put_module;
+ if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read)
+ goto out_put_module;
}
- /* No error? Great, allocate a buffer for the file, and store it
- * it in file->private_data for easy access.
- */
- buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
- if (!buffer) {
- error = -ENOMEM;
- goto Enomem;
- }
mutex_init(&buffer->mutex);
buffer->needs_read_fill = 1;
buffer->read_in_progress = false;
buffer->write_in_progress = false;
- buffer->ops = ops;
file->private_data = buffer;
- goto Done;
+ return 0;
- Einval:
- error = -EINVAL;
- goto Done;
- Eaccess:
- error = -EACCES;
- Enomem:
- module_put(attr->ca_owner);
- Done:
- if (error && item)
- config_item_put(item);
+out_put_module:
+ module_put(buffer->owner);
+out_put_item:
+ config_item_put(buffer->item);
+out_free_buffer:
+ kfree(buffer);
+out:
return error;
}
static int configfs_release(struct inode *inode, struct file *filp)
{
- struct config_item * item = to_item(filp->f_path.dentry->d_parent);
- struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
- struct module * owner = attr->ca_owner;
- struct configfs_buffer * buffer = filp->private_data;
-
- if (item)
- config_item_put(item);
- /* After this point, attr should not be accessed. */
- module_put(owner);
-
- if (buffer) {
- if (buffer->page)
- free_page((unsigned long)buffer->page);
- mutex_destroy(&buffer->mutex);
- kfree(buffer);
- }
+ struct configfs_buffer *buffer = filp->private_data;
+
+ if (buffer->item)
+ config_item_put(buffer->item);
+ module_put(buffer->owner);
+ if (buffer->page)
+ free_page((unsigned long)buffer->page);
+ mutex_destroy(&buffer->mutex);
+ kfree(buffer);
return 0;
}
static int configfs_open_file(struct inode *inode, struct file *filp)
{
- return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
+ return __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR);
}
static int configfs_open_bin_file(struct inode *inode, struct file *filp)
{
- return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
+ return __configfs_open_file(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
}
-static int configfs_release_bin_file(struct inode *inode, struct file *filp)
+static int configfs_release_bin_file(struct inode *inode, struct file *file)
{
- struct configfs_buffer *buffer = filp->private_data;
- struct dentry *dentry = filp->f_path.dentry;
- struct config_item *item = to_item(dentry->d_parent);
- struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
- ssize_t len = 0;
- int ret;
+ struct configfs_buffer *buffer = file->private_data;
buffer->read_in_progress = false;
if (buffer->write_in_progress) {
buffer->write_in_progress = false;
- len = bin_attr->write(item, buffer->bin_buffer,
+ /* result of ->release() is ignored */
+ buffer->bin_attr->write(buffer->item, buffer->bin_buffer,
buffer->bin_buffer_size);
/* vfree on NULL is safe */
@@ -489,10 +452,8 @@ static int configfs_release_bin_file(struct inode *inode, struct file *filp)
buffer->needs_read_fill = 1;
}
- ret = configfs_release(inode, filp);
- if (len < 0)
- return len;
- return ret;
+ configfs_release(inode, file);
+ return 0;
}
--
2.43.0