linux/fs/fuse/file.c
Miklos Szeredi 7c352bdf04 [PATCH] FUSE: don't allow restarting of system calls
This patch removes ability to interrupt and restart operations while there
hasn't been any side-effect.

The reason: applications.  There are some apps it seems that generate
signals at a fast rate.  This means, that if the operation cannot make
enough progress between two signals, it will be restarted for ever.  This
bug actually manifested itself with 'krusader' trying to open a file for
writing under sshfs.  Thanks to Eduard Czimbalmos for the report.

The problem can be solved just by making open() uninterruptible, because in
this case it was the truncate operation that slowed down the progress.  But
it's better to solve this by simply not allowing interrupts at all (except
SIGKILL), because applications don't expect file operations to be
interruptible anyway.  As an added bonus the code is simplified somewhat.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 14:03:48 -07:00

556 lines
14 KiB
C

/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2005 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/kernel.h>
static struct file_operations fuse_direct_io_file_operations;
int fuse_open_common(struct inode *inode, struct file *file, int isdir)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req;
struct fuse_open_in inarg;
struct fuse_open_out outarg;
struct fuse_file *ff;
int err;
err = generic_file_open(inode, file);
if (err)
return err;
/* If opening the root node, no lookup has been performed on
it, so the attributes must be refreshed */
if (get_node_id(inode) == FUSE_ROOT_ID) {
int err = fuse_do_getattr(inode);
if (err)
return err;
}
req = fuse_get_request(fc);
if (!req)
return -EINTR;
err = -ENOMEM;
ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
if (!ff)
goto out_put_request;
ff->release_req = fuse_request_alloc();
if (!ff->release_req) {
kfree(ff);
goto out_put_request;
}
memset(&inarg, 0, sizeof(inarg));
inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
req->in.h.nodeid = get_node_id(inode);
req->inode = inode;
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
req->out.numargs = 1;
req->out.args[0].size = sizeof(outarg);
req->out.args[0].value = &outarg;
request_send(fc, req);
err = req->out.h.error;
if (err) {
fuse_request_free(ff->release_req);
kfree(ff);
} else {
if (!isdir && (outarg.open_flags & FOPEN_DIRECT_IO))
file->f_op = &fuse_direct_io_file_operations;
if (!(outarg.open_flags & FOPEN_KEEP_CACHE))
invalidate_inode_pages(inode->i_mapping);
ff->fh = outarg.fh;
file->private_data = ff;
}
out_put_request:
fuse_put_request(fc, req);
return err;
}
int fuse_release_common(struct inode *inode, struct file *file, int isdir)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req = ff->release_req;
struct fuse_release_in *inarg = &req->misc.release_in;
inarg->fh = ff->fh;
inarg->flags = file->f_flags & ~O_EXCL;
req->in.h.opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
req->in.h.nodeid = get_node_id(inode);
req->inode = inode;
req->in.numargs = 1;
req->in.args[0].size = sizeof(struct fuse_release_in);
req->in.args[0].value = inarg;
request_send_background(fc, req);
kfree(ff);
/* Return value is ignored by VFS */
return 0;
}
static int fuse_open(struct inode *inode, struct file *file)
{
return fuse_open_common(inode, file, 0);
}
static int fuse_release(struct inode *inode, struct file *file)
{
return fuse_release_common(inode, file, 0);
}
static int fuse_flush(struct file *file)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req;
struct fuse_flush_in inarg;
int err;
if (fc->no_flush)
return 0;
req = fuse_get_request(fc);
if (!req)
return -EINTR;
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
req->in.h.opcode = FUSE_FLUSH;
req->in.h.nodeid = get_node_id(inode);
req->inode = inode;
req->file = file;
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (err == -ENOSYS) {
fc->no_flush = 1;
err = 0;
}
return err;
}
int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
int isdir)
{
struct inode *inode = de->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req;
struct fuse_fsync_in inarg;
int err;
if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
return 0;
req = fuse_get_request(fc);
if (!req)
return -EINTR;
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
inarg.fsync_flags = datasync ? 1 : 0;
req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
req->in.h.nodeid = get_node_id(inode);
req->inode = inode;
req->file = file;
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (err == -ENOSYS) {
if (isdir)
fc->no_fsyncdir = 1;
else
fc->no_fsync = 1;
err = 0;
}
return err;
}
static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
{
return fuse_fsync_common(file, de, datasync, 0);
}
size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count,
int isdir)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_read_in inarg;
memset(&inarg, 0, sizeof(struct fuse_read_in));
inarg.fh = ff->fh;
inarg.offset = pos;
inarg.size = count;
req->in.h.opcode = isdir ? FUSE_READDIR : FUSE_READ;
req->in.h.nodeid = get_node_id(inode);
req->inode = inode;
req->file = file;
req->in.numargs = 1;
req->in.args[0].size = sizeof(struct fuse_read_in);
req->in.args[0].value = &inarg;
req->out.argpages = 1;
req->out.argvar = 1;
req->out.numargs = 1;
req->out.args[0].size = count;
request_send(fc, req);
return req->out.args[0].size;
}
static inline size_t fuse_send_read(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos,
size_t count)
{
return fuse_send_read_common(req, file, inode, pos, count, 0);
}
static int fuse_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
loff_t pos = (loff_t) page->index << PAGE_CACHE_SHIFT;
struct fuse_req *req = fuse_get_request(fc);
int err = -EINTR;
if (!req)
goto out;
req->out.page_zeroing = 1;
req->num_pages = 1;
req->pages[0] = page;
fuse_send_read(req, file, inode, pos, PAGE_CACHE_SIZE);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err)
SetPageUptodate(page);
fuse_invalidate_attr(inode); /* atime changed */
out:
unlock_page(page);
return err;
}
static int fuse_send_readpages(struct fuse_req *req, struct file *file,
struct inode *inode)
{
loff_t pos = (loff_t) req->pages[0]->index << PAGE_CACHE_SHIFT;
size_t count = req->num_pages << PAGE_CACHE_SHIFT;
unsigned i;
req->out.page_zeroing = 1;
fuse_send_read(req, file, inode, pos, count);
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (!req->out.h.error)
SetPageUptodate(page);
unlock_page(page);
}
return req->out.h.error;
}
struct fuse_readpages_data {
struct fuse_req *req;
struct file *file;
struct inode *inode;
};
static int fuse_readpages_fill(void *_data, struct page *page)
{
struct fuse_readpages_data *data = _data;
struct fuse_req *req = data->req;
struct inode *inode = data->inode;
struct fuse_conn *fc = get_fuse_conn(inode);
if (req->num_pages &&
(req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
(req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
req->pages[req->num_pages - 1]->index + 1 != page->index)) {
int err = fuse_send_readpages(req, data->file, inode);
if (err) {
unlock_page(page);
return err;
}
fuse_reset_request(req);
}
req->pages[req->num_pages] = page;
req->num_pages ++;
return 0;
}
static int fuse_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
struct inode *inode = mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_readpages_data data;
int err;
data.file = file;
data.inode = inode;
data.req = fuse_get_request(fc);
if (!data.req)
return -EINTR;
err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
if (!err && data.req->num_pages)
err = fuse_send_readpages(data.req, file, inode);
fuse_put_request(fc, data.req);
fuse_invalidate_attr(inode); /* atime changed */
return err;
}
static size_t fuse_send_write(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_write_in inarg;
struct fuse_write_out outarg;
memset(&inarg, 0, sizeof(struct fuse_write_in));
inarg.fh = ff->fh;
inarg.offset = pos;
inarg.size = count;
req->in.h.opcode = FUSE_WRITE;
req->in.h.nodeid = get_node_id(inode);
req->inode = inode;
req->file = file;
req->in.argpages = 1;
req->in.numargs = 2;
req->in.args[0].size = sizeof(struct fuse_write_in);
req->in.args[0].value = &inarg;
req->in.args[1].size = count;
req->out.numargs = 1;
req->out.args[0].size = sizeof(struct fuse_write_out);
req->out.args[0].value = &outarg;
request_send(fc, req);
return outarg.size;
}
static int fuse_prepare_write(struct file *file, struct page *page,
unsigned offset, unsigned to)
{
/* No op */
return 0;
}
static int fuse_commit_write(struct file *file, struct page *page,
unsigned offset, unsigned to)
{
int err;
size_t nres;
unsigned count = to - offset;
struct inode *inode = page->mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
loff_t pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + offset;
struct fuse_req *req = fuse_get_request(fc);
if (!req)
return -EINTR;
req->num_pages = 1;
req->pages[0] = page;
req->page_offset = offset;
nres = fuse_send_write(req, file, inode, pos, count);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err && nres != count)
err = -EIO;
if (!err) {
pos += count;
if (pos > i_size_read(inode))
i_size_write(inode, pos);
if (offset == 0 && to == PAGE_CACHE_SIZE) {
clear_page_dirty(page);
SetPageUptodate(page);
}
}
fuse_invalidate_attr(inode);
return err;
}
static void fuse_release_user_pages(struct fuse_req *req, int write)
{
unsigned i;
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (write)
set_page_dirty_lock(page);
put_page(page);
}
}
static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
unsigned nbytes, int write)
{
unsigned long user_addr = (unsigned long) buf;
unsigned offset = user_addr & ~PAGE_MASK;
int npages;
/* This doesn't work with nfsd */
if (!current->mm)
return -EPERM;
nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
down_read(&current->mm->mmap_sem);
npages = get_user_pages(current, current->mm, user_addr, npages, write,
0, req->pages, NULL);
up_read(&current->mm->mmap_sem);
if (npages < 0)
return npages;
req->num_pages = npages;
req->page_offset = offset;
return 0;
}
static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, int write)
{
struct inode *inode = file->f_dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
size_t nmax = write ? fc->max_write : fc->max_read;
loff_t pos = *ppos;
ssize_t res = 0;
struct fuse_req *req = fuse_get_request(fc);
if (!req)
return -EINTR;
while (count) {
size_t tmp;
size_t nres;
size_t nbytes = min(count, nmax);
int err = fuse_get_user_pages(req, buf, nbytes, !write);
if (err) {
res = err;
break;
}
tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
nbytes = min(nbytes, tmp);
if (write)
nres = fuse_send_write(req, file, inode, pos, nbytes);
else
nres = fuse_send_read(req, file, inode, pos, nbytes);
fuse_release_user_pages(req, !write);
if (req->out.h.error) {
if (!res)
res = req->out.h.error;
break;
} else if (nres > nbytes) {
res = -EIO;
break;
}
count -= nres;
res += nres;
pos += nres;
buf += nres;
if (nres != nbytes)
break;
if (count)
fuse_reset_request(req);
}
fuse_put_request(fc, req);
if (res > 0) {
if (write && pos > i_size_read(inode))
i_size_write(inode, pos);
*ppos = pos;
}
fuse_invalidate_attr(inode);
return res;
}
static ssize_t fuse_direct_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return fuse_direct_io(file, buf, count, ppos, 0);
}
static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct inode *inode = file->f_dentry->d_inode;
ssize_t res;
/* Don't allow parallel writes to the same file */
down(&inode->i_sem);
res = fuse_direct_io(file, buf, count, ppos, 1);
up(&inode->i_sem);
return res;
}
static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
{
if ((vma->vm_flags & VM_SHARED)) {
if ((vma->vm_flags & VM_WRITE))
return -ENODEV;
else
vma->vm_flags &= ~VM_MAYWRITE;
}
return generic_file_mmap(file, vma);
}
static int fuse_set_page_dirty(struct page *page)
{
printk("fuse_set_page_dirty: should not happen\n");
dump_stack();
return 0;
}
static struct file_operations fuse_file_operations = {
.llseek = generic_file_llseek,
.read = generic_file_read,
.write = generic_file_write,
.mmap = fuse_file_mmap,
.open = fuse_open,
.flush = fuse_flush,
.release = fuse_release,
.fsync = fuse_fsync,
.sendfile = generic_file_sendfile,
};
static struct file_operations fuse_direct_io_file_operations = {
.llseek = generic_file_llseek,
.read = fuse_direct_read,
.write = fuse_direct_write,
.open = fuse_open,
.flush = fuse_flush,
.release = fuse_release,
.fsync = fuse_fsync,
/* no mmap and sendfile */
};
static struct address_space_operations fuse_file_aops = {
.readpage = fuse_readpage,
.prepare_write = fuse_prepare_write,
.commit_write = fuse_commit_write,
.readpages = fuse_readpages,
.set_page_dirty = fuse_set_page_dirty,
};
void fuse_init_file_inode(struct inode *inode)
{
inode->i_fop = &fuse_file_operations;
inode->i_data.a_ops = &fuse_file_aops;
}