[PATCH 4.19 052/125] configfs: stash the data we need into configfs_buffer at open time

From: Al Viro viro@zeniv.linux.org.uk

commit ff4dd081977da56566a848f071aed8fa92d604a1 upstream.

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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- fs/configfs/file.c | 229 +++++++++++++++++++++-------------------------------- 1 file changed, 95 insertions(+), 134 deletions(-)

--- a/fs/configfs/file.c +++ b/fs/configfs/file.c @@ -53,24 +53,18 @@ 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) @@ -78,15 +72,15 @@ static int fill_read_buffer(struct dentr 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; }

/** @@ -111,12 +105,13 @@ static int fill_read_buffer(struct dentr 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", @@ -153,9 +148,6 @@ configfs_read_bin_file(struct file *file 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);

@@ -170,14 +162,14 @@ configfs_read_bin_file(struct file *file

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; } @@ -190,7 +182,8 @@ configfs_read_bin_file(struct file *file 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); @@ -240,25 +233,10 @@ fill_write_buffer(struct configfs_buffer 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); }

@@ -282,13 +260,13 @@ flush_write_buffer(struct dentry * dentr 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); @@ -313,8 +291,6 @@ configfs_write_bin_file(struct file *fil 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;

@@ -330,8 +306,8 @@ configfs_write_bin_file(struct file *fil /* 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; } @@ -363,31 +339,45 @@ out: 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, @@ -395,13 +385,11 @@ static int check_perm(struct inode * ino */ 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. @@ -410,90 +398,65 @@ static int check_perm(struct inode * ino */ 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 */ @@ -503,10 +466,8 @@ static int configfs_release_bin_file(str buffer->needs_read_fill = 1; }

- ret = configfs_release(inode, filp); - if (len < 0) - return len; - return ret; + configfs_release(inode, file); + return 0; }