litmus-rt.git - The LITMUS^RT kernel.

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author	Alex Tomas <alex@clusterfs.com>	2008-07-11 19:27:31 -0400
committer	Theodore Ts'o <tytso@mit.edu>	2008-07-11 19:27:31 -0400
commit	29a814d2ee0e43c2980f33f91c1311ec06c0aa35 (patch)
tree	dfc9d45fc3194237192b6cde1069faa70fe4c260 /include/linux/mpage.h
parent	87c89c232c8f7b3820c33c3b9bc803e9358027da (diff)

vfs: add hooks for ext4's delayed allocation support

Export mpage_bio_submit() and __mpage_writepage() for the benefit of ext4's delayed allocation support. Also change __block_write_full_page so that if buffers that have the BH_Delay flag set it will call get_block() to get the physical block allocated, just as in the !BH_Mapped case. Signed-off-by: Alex Tomas <alex@clusterfs.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Diffstat (limited to 'include/linux/mpage.h')

-rw-r--r--

include/linux/mpage.h

1 files changed, 10 insertions, 0 deletions

  */
 #ifdef CONFIG_BLOCK
+struct mpage_data {
+        struct bio *bio;
+        sector_t last_block_in_bio;
+        get_block_t *get_block;
+        unsigned use_writepage;
+};
 struct writeback_control;
+struct bio *mpage_bio_submit(int rw, struct bio *bio);
 int mpage_readpages(struct address_space *mapping, struct list_head *pages,
                                 unsigned nr_pages, get_block_t get_block);
 int mpage_readpage(struct page *page, get_block_t get_block);
+int __mpage_writepage(struct page *page, struct writeback_control *wbc,
+                      void *data);
 int mpage_writepages(struct address_space *mapping,
                 struct writeback_control *wbc, get_block_t get_block);
 int mpage_writepage(struct page *page, get_block_t *get_block,

/* * file.c - operations for regular (text) files. */ #include <linux/module.h> #include <linux/fsnotify.h> #include <linux/kobject.h> #include <linux/namei.h> #include <linux/poll.h> #include <asm/uaccess.h> #include <asm/semaphore.h> #include "sysfs.h" #define to_subsys(k) container_of(k,struct subsystem,kset.kobj) #define to_sattr(a) container_of(a,struct subsys_attribute,attr) /* * Subsystem file operations. * These operations allow subsystems to have files that can be * read/written. */ static ssize_t subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page) { struct subsystem * s = to_subsys(kobj); struct subsys_attribute * sattr = to_sattr(attr); ssize_t ret = -EIO; if (sattr->show) ret = sattr->show(s,page); return ret; } static ssize_t subsys_attr_store(struct kobject * kobj, struct attribute * attr, const char * page, size_t count) { struct subsystem * s = to_subsys(kobj); struct subsys_attribute * sattr = to_sattr(attr); ssize_t ret = -EIO; if (sattr->store) ret = sattr->store(s,page,count); return ret; } static struct sysfs_ops subsys_sysfs_ops = { .show = subsys_attr_show, .store = subsys_attr_store, }; struct sysfs_buffer { size_t count; loff_t pos; char * page; struct sysfs_ops * ops; struct semaphore sem; int needs_read_fill; int event; }; /** * fill_read_buffer - allocate and fill buffer from object. * @dentry: dentry pointer. * @buffer: data buffer for file. * * Allocate @buffer->page, if it hasn't been already, then call the * kobject'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 sysfs_buffer * buffer) { struct sysfs_dirent * sd = dentry->d_fsdata; struct attribute * attr = to_attr(dentry); struct kobject * kobj = to_kobj(dentry->d_parent); struct sysfs_ops * ops = buffer->ops; int ret = 0; ssize_t count; if (!buffer->page) buffer->page = (char *) get_zeroed_page(GFP_KERNEL); if (!buffer->page) return -ENOMEM; buffer->event = atomic_read(&sd->s_event); count = ops->show(kobj,attr,buffer->page); buffer->needs_read_fill = 0; BUG_ON(count > (ssize_t)PAGE_SIZE); if (count >= 0) buffer->count = count; else ret = count; return ret; } /** * flush_read_buffer - push buffer to userspace. * @buffer: data buffer for file. * @buf: user-passed buffer. * @count: number of bytes requested. * @ppos: file position. * * Copy the buffer we filled in fill_read_buffer() to userspace. * This is done at the reader's leisure, copying and advancing * the amount they specify each time. * This may be called continuously until the buffer is empty. */ static int flush_read_buffer(struct sysfs_buffer * buffer, char __user * buf, size_t count, loff_t * ppos) { int error; if (*ppos > buffer->count) return 0; if (count > (buffer->count - *ppos)) count = buffer->count - *ppos; error = copy_to_user(buf,buffer->page + *ppos,count); if (!error) *ppos += count; return error ? -EFAULT : count; } /** * sysfs_read_file - read an attribute. * @file: file pointer. * @buf: buffer to fill. * @count: number of bytes to read. * @ppos: starting offset in file. * * Userspace wants to read an attribute file. The attribute descriptor * is in the file's ->d_fsdata. The target object is in the directory's * ->d_fsdata. * * We call fill_read_buffer() to allocate and fill the buffer from the * object's show() method exactly once (if the read is happening from * the beginning of the file). That should fill the entire buffer with * all the data the object has to offer for that attribute. * We then call flush_read_buffer() to copy the buffer to userspace * in the increments specified. */ static ssize_t sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct sysfs_buffer * buffer = file->private_data; ssize_t retval = 0; down(&buffer->sem); if (buffer->needs_read_fill) { if ((retval = fill_read_buffer(file->f_dentry,buffer))) goto out; } pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n", __FUNCTION__, count, *ppos, buffer->page); retval = flush_read_buffer(buffer,buf,count,ppos); out: up(&buffer->sem); return retval; } /** * fill_write_buffer - copy buffer from userspace. * @buffer: data buffer for file. * @buf: data from user. * @count: number of bytes in @userbuf. * * Allocate @buffer->page if it hasn't been already, then * copy the user-supplied buffer into it. */ static int fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count) { int error; if (!buffer->page) buffer->page = (char *)get_zeroed_page(GFP_KERNEL); if (!buffer->page) return -ENOMEM; if (count >= PAGE_SIZE) count = PAGE_SIZE - 1; error = copy_from_user(buffer->page,buf,count); buffer->needs_read_fill = 1; return error ? -EFAULT : count; } /** * flush_write_buffer - push buffer to kobject. * @dentry: dentry to the attribute * @buffer: data buffer for file. * @count: number of bytes * * Get the correct pointers for the kobject 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 sysfs_buffer * buffer, size_t count) { struct attribute * attr = to_attr(dentry); struct kobject * kobj = to_kobj(dentry->d_parent); struct sysfs_ops * ops = buffer->ops; return ops->store(kobj,attr,buffer->page,count); } /** * sysfs_write_file - write an attribute. * @file: file pointer * @buf: data to write * @count: number of bytes * @ppos: starting offset * * Similar to sysfs_read_file(), though working in the opposite direction. * We allocate and fill the data from the user in fill_write_buffer(), * then push it to the kobject in flush_write_buffer(). * There is no easy way for us to know if userspace is only doing a partial * write, so we don't support them. We expect the entire buffer to come * on the first write. * Hint: if you're writing a value, first read the file, modify only the * the value you're changing, then write entire buffer back. */ static ssize_t sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { struct sysfs_buffer * buffer = file->private_data; ssize_t len; down(&buffer->sem); len = fill_write_buffer(buffer, buf, count); if (len > 0) len = flush_write_buffer(file->f_dentry, buffer, len); if (len > 0) *ppos += len; up(&buffer->sem); return len; } static int check_perm(struct inode * inode, struct file * file) { struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent); struct attribute * attr = to_attr(file->f_dentry); struct sysfs_buffer * buffer; struct sysfs_ops * ops = NULL; int error = 0; if (!kobj || !attr) goto Einval; /* Grab the module reference for this attribute if we have one */ if (!try_module_get(attr->owner)) { error = -ENODEV; goto Done; } /* if the kobject has no ktype, then we assume that it is a subsystem * itself, and use ops for it. */ if (kobj->kset && kobj->kset->ktype) ops = kobj->kset->ktype->sysfs_ops; else if (kobj->ktype) ops = kobj->ktype->sysfs_ops; else ops = &subsys_sysfs_ops; /* No sysfs operations, either from having no subsystem, * or the subsystem have no operations. */ if (!ops) goto Eaccess; /* File needs write support. * The inode's perms must say it's ok, * and we must have a store method. */ if (file->f_mode & FMODE_WRITE) { if (!(inode->i_mode & S_IWUGO) || !ops->store) goto Eaccess; } /* File needs read support. * The inode's perms must say it's ok, and we there * must be a show method for it. */ if (file->f_mode & FMODE_READ) { if (!(inode->i_mode & S_IRUGO) || !ops->show) goto Eaccess; } /* No error? Great, allocate a buffer for the file, and store it * it in file->private_data for easy access. */ buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL); if (buffer) { init_MUTEX(&buffer->sem); buffer->needs_read_fill = 1; buffer->ops = ops; file->private_data = buffer; } else error = -ENOMEM; goto Done; Einval: error = -EINVAL; goto Done; Eaccess: error = -EACCES; module_put(attr->owner); Done: if (error && kobj) kobject_put(kobj); return error; } static int sysfs_open_file(struct inode * inode, struct file * filp) { return check_perm(inode,filp); } static int sysfs_release(struct inode * inode, struct file * filp) { struct kobject * kobj = to_kobj(filp->f_dentry->d_parent); struct attribute * attr = to_attr(filp->f_dentry); struct module * owner = attr->owner; struct sysfs_buffer * buffer = filp->private_data; if (kobj) kobject_put(kobj); /* After this point, attr should not be accessed. */ module_put(owner); if (buffer) { if (buffer->page) free_page((unsigned long)buffer->page); kfree(buffer); } return 0; } /* Sysfs attribute files are pollable. The idea is that you read * the content and then you use 'poll' or 'select' to wait for * the content to change. When the content changes (assuming the * manager for the kobject supports notification), poll will * return POLLERR|POLLPRI, and select will return the fd whether * it is waiting for read, write, or exceptions. * Once poll/select indicates that the value has changed, you * need to close and re-open the file, as simply seeking and reading * again will not get new data, or reset the state of 'poll'. * Reminder: this only works for attributes which actively support * it, and it is not possible to test an attribute from userspace * to see if it supports poll (Nether 'poll' or 'select' return * an appropriate error code). When in doubt, set a suitable timeout value. */


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