diff options
author | Pantelis Antoniou <pantelis.antoniou@konsulko.com> | 2015-10-22 23:30:04 +0300 |
---|---|---|
committer | Christoph Hellwig <hch@lst.de> | 2016-01-04 12:31:46 +0100 |
commit | 03607ace807b414eab46323c794b6fb8fcc2d48c (patch) | |
tree | a192ae4376e5db9eb02e2563d3c12a7312e677ba /fs/configfs/file.c | |
parent | 4ef7675344d687a0ef5b0d7c0cee12da005870c0 (diff) |
configfs: implement binary attributes
ConfigFS lacked binary attributes up until now. This patch
introduces support for binary attributes in a somewhat similar
manner of sysfs binary attributes albeit with changes that
fit the configfs usage model.
Problems that configfs binary attributes fix are everything that
requires a binary blob as part of the configuration of a resource,
such as bitstream loading for FPGAs, DTBs for dynamically created
devices etc.
Look at Documentation/filesystems/configfs/configfs.txt for internals
and howto use them.
This patch is against linux-next as of today that contains
Christoph's configfs rework.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[hch: folded a fix from Geert Uytterhoeven <geert+renesas@glider.be>]
[hch: a few tiny updates based on review feedback]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/configfs/file.c')
-rw-r--r-- | fs/configfs/file.c | 255 |
1 files changed, 246 insertions, 9 deletions
diff --git a/fs/configfs/file.c b/fs/configfs/file.c index d39099ea7df7..3687187c8ea5 100644 --- a/fs/configfs/file.c +++ b/fs/configfs/file.c @@ -28,6 +28,7 @@ #include <linux/module.h> #include <linux/slab.h> #include <linux/mutex.h> +#include <linux/vmalloc.h> #include <asm/uaccess.h> #include <linux/configfs.h> @@ -48,6 +49,10 @@ struct configfs_buffer { struct configfs_item_operations * ops; struct mutex mutex; int needs_read_fill; + bool read_in_progress; + bool write_in_progress; + char *bin_buffer; + int bin_buffer_size; }; @@ -123,6 +128,87 @@ out: return retval; } +/** + * configfs_read_bin_file - read a binary attribute. + * @file: file pointer. + * @buf: buffer to fill. + * @count: number of bytes to read. + * @ppos: starting offset in file. + * + * Userspace wants to read a binary attribute file. The attribute + * descriptor is in the file's ->d_fsdata. The target item is in the + * directory's ->d_fsdata. + * + * We check whether we need to refill the buffer. If so we will + * call the attributes' attr->read() twice. The first time we + * will pass a NULL as a buffer pointer, which the attributes' method + * will use to return the size of the buffer required. If no error + * occurs we will allocate the buffer using vmalloc and call + * attr->read() again passing that buffer as an argument. + * Then we just copy to user-space using simple_read_from_buffer. + */ + +static ssize_t +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); + + mutex_lock(&buffer->mutex); + + /* we don't support switching read/write modes */ + if (buffer->write_in_progress) { + retval = -ETXTBSY; + goto out; + } + buffer->read_in_progress = 1; + + if (buffer->needs_read_fill) { + /* perform first read with buf == NULL to get extent */ + len = bin_attr->read(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) { + retval = -EFBIG; + goto out; + } + + buffer->bin_buffer = vmalloc(len); + if (buffer->bin_buffer == NULL) { + retval = -ENOMEM; + goto out; + } + buffer->bin_buffer_size = len; + + /* perform second read to fill buffer */ + len = bin_attr->read(item, buffer->bin_buffer, len); + if (len < 0) { + retval = len; + vfree(buffer->bin_buffer); + buffer->bin_buffer_size = 0; + buffer->bin_buffer = NULL; + goto out; + } + + buffer->needs_read_fill = 0; + } + + retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer, + buffer->bin_buffer_size); +out: + mutex_unlock(&buffer->mutex); + return retval; +} + /** * fill_write_buffer - copy buffer from userspace. @@ -209,10 +295,80 @@ configfs_write_file(struct file *file, const char __user *buf, size_t count, lof return len; } -static int check_perm(struct inode * inode, struct file * file) +/** + * configfs_write_bin_file - write a binary attribute. + * @file: file pointer + * @buf: data to write + * @count: number of bytes + * @ppos: starting offset + * + * Writing to a binary attribute file is similar to a normal read. + * We buffer the consecutive writes (binary attribute files do not + * support lseek) in a continuously growing buffer, but we don't + * commit until the close of the file. + */ + +static ssize_t +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; + + mutex_lock(&buffer->mutex); + + /* we don't support switching read/write modes */ + if (buffer->read_in_progress) { + len = -ETXTBSY; + goto out; + } + buffer->write_in_progress = 1; + + /* buffer grows? */ + if (*ppos + count > buffer->bin_buffer_size) { + + if (bin_attr->cb_max_size && + *ppos + count > bin_attr->cb_max_size) { + len = -EFBIG; + } + + tbuf = vmalloc(*ppos + count); + if (tbuf == NULL) { + len = -ENOMEM; + goto out; + } + + /* copy old contents */ + if (buffer->bin_buffer) { + memcpy(tbuf, buffer->bin_buffer, + buffer->bin_buffer_size); + vfree(buffer->bin_buffer); + } + + /* clear the new area */ + memset(tbuf + buffer->bin_buffer_size, 0, + *ppos + count - buffer->bin_buffer_size); + buffer->bin_buffer = tbuf; + buffer->bin_buffer_size = *ppos + count; + } + + len = simple_write_to_buffer(buffer->bin_buffer, + buffer->bin_buffer_size, ppos, buf, count); + if (len > 0) + *ppos += len; +out: + mutex_unlock(&buffer->mutex); + return len; +} + +static int check_perm(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; @@ -220,6 +376,9 @@ static int check_perm(struct inode * inode, struct file * file) if (!item || !attr) goto Einval; + if (type & CONFIGFS_ITEM_BIN_ATTR) + bin_attr = to_bin_attr(file->f_path.dentry); + /* Grab the module reference for this attribute if we have one */ if (!try_module_get(attr->ca_owner)) { error = -ENODEV; @@ -236,9 +395,14 @@ static int check_perm(struct inode * inode, struct file * file) * and we must have a store method. */ if (file->f_mode & FMODE_WRITE) { - if (!(inode->i_mode & S_IWUGO) || !attr->store) + if (!(inode->i_mode & S_IWUGO)) + goto Eaccess; + + if ((type & CONFIGFS_ITEM_ATTR) && !attr->store) goto Eaccess; + if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write) + goto Eaccess; } /* File needs read support. @@ -246,7 +410,13 @@ static int check_perm(struct inode * inode, struct file * file) * must be a show method for it. */ if (file->f_mode & FMODE_READ) { - if (!(inode->i_mode & S_IRUGO) || !attr->show) + if (!(inode->i_mode & S_IRUGO)) + goto Eaccess; + + if ((type & CONFIGFS_ITEM_ATTR) && !attr->show) + goto Eaccess; + + if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read) goto Eaccess; } @@ -260,6 +430,8 @@ static int check_perm(struct inode * inode, struct file * file) } mutex_init(&buffer->mutex); buffer->needs_read_fill = 1; + buffer->read_in_progress = 0; + buffer->write_in_progress = 0; buffer->ops = ops; file->private_data = buffer; goto Done; @@ -277,12 +449,7 @@ static int check_perm(struct inode * inode, struct file * file) return error; } -static int configfs_open_file(struct inode * inode, struct file * filp) -{ - return check_perm(inode,filp); -} - -static int configfs_release(struct inode * inode, struct file * filp) +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); @@ -303,6 +470,47 @@ static int configfs_release(struct inode * inode, struct file * filp) return 0; } +static int configfs_open_file(struct inode *inode, struct file *filp) +{ + return check_perm(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); +} + +static int configfs_release_bin_file(struct inode *inode, struct file *filp) +{ + 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; + + buffer->read_in_progress = 0; + + if (buffer->write_in_progress) { + buffer->write_in_progress = 0; + + len = bin_attr->write(item, buffer->bin_buffer, + buffer->bin_buffer_size); + + /* vfree on NULL is safe */ + vfree(buffer->bin_buffer); + buffer->bin_buffer = NULL; + buffer->bin_buffer_size = 0; + buffer->needs_read_fill = 1; + } + + ret = configfs_release(inode, filp); + if (len < 0) + return len; + return ret; +} + + const struct file_operations configfs_file_operations = { .read = configfs_read_file, .write = configfs_write_file, @@ -311,6 +519,14 @@ const struct file_operations configfs_file_operations = { .release = configfs_release, }; +const struct file_operations configfs_bin_file_operations = { + .read = configfs_read_bin_file, + .write = configfs_write_bin_file, + .llseek = NULL, /* bin file is not seekable */ + .open = configfs_open_bin_file, + .release = configfs_release_bin_file, +}; + /** * configfs_create_file - create an attribute file for an item. * @item: item we're creating for. @@ -332,3 +548,24 @@ int configfs_create_file(struct config_item * item, const struct configfs_attrib return error; } +/** + * configfs_create_bin_file - create a binary attribute file for an item. + * @item: item we're creating for. + * @attr: atrribute descriptor. + */ + +int configfs_create_bin_file(struct config_item *item, + const struct configfs_bin_attribute *bin_attr) +{ + struct dentry *dir = item->ci_dentry; + struct configfs_dirent *parent_sd = dir->d_fsdata; + umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG; + int error = 0; + + mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_NORMAL); + error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode, + CONFIGFS_ITEM_BIN_ATTR); + mutex_unlock(&dir->d_inode->i_mutex); + + return error; +} |