Revision c37bc682e30b8027054356214eb8a3aafbda8e37 authored by Johan Hovold on 04 March 2015, 09:39:07 UTC, committed by Greg Kroah-Hartman on 07 March 2015, 02:44:15 UTC
Currently tty_wait_until_sent may take up to twice as long as the requested timeout while waiting for driver and hardware buffers to drain. Fix this by taking the remaining number of jiffies after waiting for driver buffers to drain into account so that the timeout actually becomes a maximum timeout as it is documented to be. Note that this specifically implies tighter timings when closing a port as a consequence of actually honouring the port closing-wait setting for drivers relying on tty_wait_until_sent_from_close (e.g. via tty_port_close_start). Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 parent 79fbf4a
file.c
/*
* fs/logfs/file.c - prepare_write, commit_write and friends
*
* As should be obvious for Linux kernel code, license is GPLv2
*
* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
*/
#include "logfs.h"
#include <linux/sched.h>
#include <linux/writeback.h>
static int logfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
struct inode *inode = mapping->host;
struct page *page;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page)
return -ENOMEM;
*pagep = page;
if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
return 0;
if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
unsigned start = pos & (PAGE_CACHE_SIZE - 1);
unsigned end = start + len;
/* Reading beyond i_size is simple: memset to zero */
zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
return 0;
}
return logfs_readpage_nolock(page);
}
static int logfs_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied, struct page *page,
void *fsdata)
{
struct inode *inode = mapping->host;
pgoff_t index = page->index;
unsigned start = pos & (PAGE_CACHE_SIZE - 1);
unsigned end = start + copied;
int ret = 0;
BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
BUG_ON(page->index > I3_BLOCKS);
if (copied < len) {
/*
* Short write of a non-initialized paged. Just tell userspace
* to retry the entire page.
*/
if (!PageUptodate(page)) {
copied = 0;
goto out;
}
}
if (copied == 0)
goto out; /* FIXME: do we need to update inode? */
if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
mark_inode_dirty_sync(inode);
}
SetPageUptodate(page);
if (!PageDirty(page)) {
if (!get_page_reserve(inode, page))
__set_page_dirty_nobuffers(page);
else
ret = logfs_write_buf(inode, page, WF_LOCK);
}
out:
unlock_page(page);
page_cache_release(page);
return ret ? ret : copied;
}
int logfs_readpage(struct file *file, struct page *page)
{
int ret;
ret = logfs_readpage_nolock(page);
unlock_page(page);
return ret;
}
/* Clear the page's dirty flag in the radix tree. */
/* TODO: mucking with PageWriteback is silly. Add a generic function to clear
* the dirty bit from the radix tree for filesystems that don't have to wait
* for page writeback to finish (i.e. any compressing filesystem).
*/
static void clear_radix_tree_dirty(struct page *page)
{
BUG_ON(PagePrivate(page) || page->private);
set_page_writeback(page);
end_page_writeback(page);
}
static int __logfs_writepage(struct page *page)
{
struct inode *inode = page->mapping->host;
int err;
err = logfs_write_buf(inode, page, WF_LOCK);
if (err)
set_page_dirty(page);
else
clear_radix_tree_dirty(page);
unlock_page(page);
return err;
}
static int logfs_writepage(struct page *page, struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
loff_t i_size = i_size_read(inode);
pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
u64 bix;
level_t level;
log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
page);
logfs_unpack_index(page->index, &bix, &level);
/* Indirect blocks are never truncated */
if (level != 0)
return __logfs_writepage(page);
/*
* TODO: everything below is a near-verbatim copy of nobh_writepage().
* The relevant bits should be factored out after logfs is merged.
*/
/* Is the page fully inside i_size? */
if (bix < end_index)
return __logfs_writepage(page);
/* Is the page fully outside i_size? (truncate in progress) */
offset = i_size & (PAGE_CACHE_SIZE-1);
if (bix > end_index || offset == 0) {
unlock_page(page);
return 0; /* don't care */
}
/*
* The page straddles i_size. It must be zeroed out on each and every
* writepage invokation because it may be mmapped. "A file is mapped
* in multiples of the page size. For a file that is not a multiple of
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
zero_user_segment(page, offset, PAGE_CACHE_SIZE);
return __logfs_writepage(page);
}
static void logfs_invalidatepage(struct page *page, unsigned int offset,
unsigned int length)
{
struct logfs_block *block = logfs_block(page);
if (block->reserved_bytes) {
struct super_block *sb = page->mapping->host->i_sb;
struct logfs_super *super = logfs_super(sb);
super->s_dirty_pages -= block->reserved_bytes;
block->ops->free_block(sb, block);
BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
} else
move_page_to_btree(page);
BUG_ON(PagePrivate(page) || page->private);
}
static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
{
return 0; /* None of these are easy to release */
}
long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(file);
struct logfs_inode *li = logfs_inode(inode);
unsigned int oldflags, flags;
int err;
switch (cmd) {
case FS_IOC_GETFLAGS:
flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
return put_user(flags, (int __user *)arg);
case FS_IOC_SETFLAGS:
if (IS_RDONLY(inode))
return -EROFS;
if (!inode_owner_or_capable(inode))
return -EACCES;
err = get_user(flags, (int __user *)arg);
if (err)
return err;
mutex_lock(&inode->i_mutex);
oldflags = li->li_flags;
flags &= LOGFS_FL_USER_MODIFIABLE;
flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
li->li_flags = flags;
mutex_unlock(&inode->i_mutex);
inode->i_ctime = CURRENT_TIME;
mark_inode_dirty_sync(inode);
return 0;
default:
return -ENOTTY;
}
}
int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
struct super_block *sb = file->f_mapping->host->i_sb;
struct inode *inode = file->f_mapping->host;
int ret;
ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
if (ret)
return ret;
mutex_lock(&inode->i_mutex);
logfs_get_wblocks(sb, NULL, WF_LOCK);
logfs_write_anchor(sb);
logfs_put_wblocks(sb, NULL, WF_LOCK);
mutex_unlock(&inode->i_mutex);
return 0;
}
static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = dentry->d_inode;
int err = 0;
err = inode_change_ok(inode, attr);
if (err)
return err;
if (attr->ia_valid & ATTR_SIZE) {
err = logfs_truncate(inode, attr->ia_size);
if (err)
return err;
}
setattr_copy(inode, attr);
mark_inode_dirty(inode);
return 0;
}
const struct inode_operations logfs_reg_iops = {
.setattr = logfs_setattr,
};
const struct file_operations logfs_reg_fops = {
.read_iter = generic_file_read_iter,
.write_iter = generic_file_write_iter,
.fsync = logfs_fsync,
.unlocked_ioctl = logfs_ioctl,
.llseek = generic_file_llseek,
.mmap = generic_file_readonly_mmap,
.open = generic_file_open,
.read = new_sync_read,
.write = new_sync_write,
};
const struct address_space_operations logfs_reg_aops = {
.invalidatepage = logfs_invalidatepage,
.readpage = logfs_readpage,
.releasepage = logfs_releasepage,
.set_page_dirty = __set_page_dirty_nobuffers,
.writepage = logfs_writepage,
.writepages = generic_writepages,
.write_begin = logfs_write_begin,
.write_end = logfs_write_end,
};
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