/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2018 Miklos Szeredi <[email protected]>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/iversion.h>
#include <linux/posix_acl.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
static bool fuse_use_readdirplus(struct inode *dir, struct dir_context *ctx)
{
struct fuse_conn *fc = get_fuse_conn(dir);
struct fuse_inode *fi = get_fuse_inode(dir);
if (!fc->do_readdirplus)
return false;
if (!fc->readdirplus_auto)
return true;
if (test_and_clear_bit(FUSE_I_ADVISE_RDPLUS, &fi->state))
return true;
if (ctx->pos == 0)
return true;
return false;
}
static void fuse_add_dirent_to_cache(struct file *file,
struct fuse_dirent *dirent, loff_t pos)
{
struct fuse_inode *fi = get_fuse_inode(file_inode(file));
size_t reclen = FUSE_DIRENT_SIZE(dirent);
pgoff_t index;
struct page *page;
loff_t size;
u64 version;
unsigned int offset;
void *addr;
spin_lock(&fi->rdc.lock);
/*
* Is cache already completed? Or this entry does not go at the end of
* cache?
*/
if (fi->rdc.cached || pos != fi->rdc.pos) {
spin_unlock(&fi->rdc.lock);
return;
}
version = fi->rdc.version;
size = fi->rdc.size;
offset = size & ~PAGE_MASK;
index = size >> PAGE_SHIFT;
/* Dirent doesn't fit in current page? Jump to next page. */
if (offset + reclen > PAGE_SIZE) {
index++;
offset = 0;
}
spin_unlock(&fi->rdc.lock);
if (offset) {
page = find_lock_page(file->f_mapping, index);
} else {
page = find_or_create_page(file->f_mapping, index,
mapping_gfp_mask(file->f_mapping));
}
if (!page)
return;
spin_lock(&fi->rdc.lock);
/* Raced with another readdir */
if (fi->rdc.version != version || fi->rdc.size != size ||
WARN_ON(fi->rdc.pos != pos))
goto unlock;
addr = kmap_local_page(page);
if (!offset) {
clear_page(addr);
SetPageUptodate(page);
}
memcpy(addr + offset, dirent, reclen);
kunmap_local(addr);
fi->rdc.size = (index << PAGE_SHIFT) + offset + reclen;
fi->rdc.pos = dirent->off;
unlock:
spin_unlock(&fi->rdc.lock);
unlock_page(page);
put_page(page);
}
static void fuse_readdir_cache_end(struct file *file, loff_t pos)
{
struct fuse_inode *fi = get_fuse_inode(file_inode(file));
loff_t end;
spin_lock(&fi->rdc.lock);
/* does cache end position match current position? */
if (fi->rdc.pos != pos) {
spin_unlock(&fi->rdc.lock);
return;
}
fi->rdc.cached = true;
end = ALIGN(fi->rdc.size, PAGE_SIZE);
spin_unlock(&fi->rdc.lock);
/* truncate unused tail of cache */
truncate_inode_pages(file->f_mapping, end);
}
static bool fuse_emit(struct file *file, struct dir_context *ctx,
struct fuse_dirent *dirent)
{
struct fuse_file *ff = file->private_data;
if (ff->open_flags & FOPEN_CACHE_DIR)
fuse_add_dirent_to_cache(file, dirent, ctx->pos);
return dir_emit(ctx, dirent->name, dirent->namelen, dirent->ino,
dirent->type);
}
static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
struct dir_context *ctx)
{
while (nbytes >= FUSE_NAME_OFFSET) {
struct fuse_dirent *dirent = (struct fuse_dirent *) buf;
size_t reclen = FUSE_DIRENT_SIZE(dirent);
if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
return -EIO;
if (reclen > nbytes)
break;
if (memchr(dirent->name, '/', dirent->namelen) != NULL)
return -EIO;
if (!fuse_emit(file, ctx, dirent))
break;
buf += reclen;
nbytes -= reclen;
ctx->pos = dirent->off;
}
return 0;
}
static int fuse_direntplus_link(struct file *file,
struct fuse_direntplus *direntplus,
u64 attr_version)
{
struct fuse_entry_out *o = &direntplus->entry_out;
struct fuse_dirent *dirent = &direntplus->dirent;
struct dentry *parent = file->f_path.dentry;
struct qstr name = QSTR_INIT(dirent->name, dirent->namelen);
struct dentry *dentry;
struct dentry *alias;
struct inode *dir = d_inode(parent);
struct fuse_conn *fc;
struct inode *inode;
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
if (!o->nodeid) {
/*
* Unlike in the case of fuse_lookup, zero nodeid does not mean
* ENOENT. Instead, it only means the userspace filesystem did
* not want to return attributes/handle for this entry.
*
* So do nothing.
*/
return 0;
}
if (name.name[0] == '.') {
/*
* We could potentially refresh the attributes of the directory
* and its parent?
*/
if (name.len == 1)
return 0;
if (name.name[1] == '.' && name.len == 2)
return 0;
}
if (invalid_nodeid(o->nodeid))
return -EIO;
if (fuse_invalid_attr(&o->attr))
return -EIO;
fc = get_fuse_conn(dir);
name.hash = full_name_hash(parent, name.name, name.len);
dentry = d_lookup(parent, &name);
if (!dentry) {
retry:
dentry = d_alloc_parallel(parent, &name, &wq);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
}
if (!d_in_lookup(dentry)) {
struct fuse_inode *fi;
inode = d_inode(dentry);
if (inode && get_node_id(inode) != o->nodeid)
inode = NULL;
if (!inode ||
fuse_stale_inode(inode, o->generation, &o->attr)) {
if (inode)
fuse_make_bad(inode);
d_invalidate(dentry);
dput(dentry);
goto retry;
}
if (fuse_is_bad(inode)) {
dput(dentry);
return -EIO;
}
fi = get_fuse_inode(inode);
spin_lock(&fi->lock);
fi->nlookup++;
spin_unlock(&fi->lock);
forget_all_cached_acls(inode);
fuse_change_attributes(inode, &o->attr, NULL,
ATTR_TIMEOUT(o),
attr_version);
/*
* The other branch comes via fuse_iget()
* which bumps nlookup inside
*/
} else {
inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
&o->attr, ATTR_TIMEOUT(o),
attr_version);
if (!inode)
inode = ERR_PTR(-ENOMEM);
alias = d_splice_alias(inode, dentry);
d_lookup_done(dentry);
if (alias) {
dput(dentry);
dentry = alias;
}
if (IS_ERR(dentry)) {
if (!IS_ERR(inode)) {
struct fuse_inode *fi = get_fuse_inode(inode);
spin_lock(&fi->lock);
fi->nlookup--;
spin_unlock(&fi->lock);
}
return PTR_ERR(dentry);
}
}
if (fc->readdirplus_auto)
set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
fuse_change_entry_timeout(dentry, o);
dput(dentry);
return 0;
}
static void fuse_force_forget(struct file *file, u64 nodeid)
{
struct inode *inode = file_inode(file);
struct fuse_mount *fm = get_fuse_mount(inode);
struct fuse_forget_in inarg;
FUSE_ARGS(args);
memset(&inarg, 0, sizeof(inarg));
inarg.nlookup = 1;
args.opcode = FUSE_FORGET;
args.nodeid = nodeid;
args.in_numargs = 1;
args.in_args[0].size = sizeof(inarg);
args.in_args[0].value = &inarg;
args.force = true;
args.noreply = true;
fuse_simple_request(fm, &args);
/* ignore errors */
}
static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
struct dir_context *ctx, u64 attr_version)
{
struct fuse_direntplus *direntplus;
struct fuse_dirent *dirent;
size_t reclen;
int over = 0;
int ret;
while (nbytes >= FUSE_NAME_OFFSET_DIRENTPLUS) {
direntplus = (struct fuse_direntplus *) buf;
dirent = &direntplus->dirent;
reclen = FUSE_DIRENTPLUS_SIZE(direntplus);
if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
return -EIO;
if (reclen > nbytes)
break;
if (memchr(dirent->name, '/', dirent->namelen) != NULL)
return -EIO;
if (!over) {
/* We fill entries into dstbuf only as much as
it can hold. But we still continue iterating
over remaining entries to link them. If not,
we need to send a FORGET for each of those
which we did not link.
*/
over = !fuse_emit(file, ctx, dirent);
if (!over)
ctx->pos = dirent->off;
}
buf += reclen;
nbytes -= reclen;
ret = fuse_direntplus_link(file, direntplus, attr_version);
if (ret)
fuse_force_forget(file, direntplus->entry_out.nodeid);
}
return 0;
}
static int fuse_readdir_uncached(struct file *file, struct dir_context *ctx)
{
int plus;
ssize_t res;
struct page *page;
struct inode *inode = file_inode(file);
struct fuse_mount *fm = get_fuse_mount(inode);
struct fuse_io_args ia = {};
struct fuse_args_pages *ap = &ia.ap;
struct fuse_page_desc desc = { .length = PAGE_SIZE };
u64 attr_version = 0;
bool locked;
page = alloc_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
plus = fuse_use_readdirplus(inode, ctx);
ap->args.out_pages = true;
ap->num_pages = 1;
ap->pages = &page;
ap->descs = &desc;
if (plus) {
attr_version = fuse_get_attr_version(fm->fc);
fuse_read_args_fill(&ia, file, ctx->pos, PAGE_SIZE,
FUSE_READDIRPLUS);
} else {
fuse_read_args_fill(&ia, file, ctx->pos, PAGE_SIZE,
FUSE_READDIR);
}
locked = fuse_lock_inode(inode);
res = fuse_simple_request(fm, &ap->args);
fuse_unlock_inode(inode, locked);
if (res >= 0) {
if (!res) {
struct fuse_file *ff = file->private_data;
if (ff->open_flags & FOPEN_CACHE_DIR)
fuse_readdir_cache_end(file, ctx->pos);
} else if (plus) {
res = parse_dirplusfile(page_address(page), res,
file, ctx, attr_version);
} else {
res = parse_dirfile(page_address(page), res, file,
ctx);
}
}
__free_page(page);
fuse_invalidate_atime(inode);
return res;
}
enum fuse_parse_result {
FOUND_ERR = -1,
FOUND_NONE = 0,
FOUND_SOME,
FOUND_ALL,
};
static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff,
void *addr, unsigned int size,
struct dir_context *ctx)
{
unsigned int offset = ff->readdir.cache_off & ~PAGE_MASK;
enum fuse_parse_result res = FOUND_NONE;
WARN_ON(offset >= size);
for (;;) {
struct fuse_dirent *dirent = addr + offset;
unsigned int nbytes = size - offset;
size_t reclen;
if (nbytes < FUSE_NAME_OFFSET || !dirent->namelen)
break;
reclen = FUSE_DIRENT_SIZE(dirent); /* derefs ->namelen */
if (WARN_ON(dirent->namelen > FUSE_NAME_MAX))
return FOUND_ERR;
if (WARN_ON(reclen > nbytes))
return FOUND_ERR;
if (WARN_ON(memchr(dirent->name, '/', dirent->namelen) != NULL))
return FOUND_ERR;
if (ff->readdir.pos == ctx->pos) {
res = FOUND_SOME;
if (!dir_emit(ctx, dirent->name, dirent->namelen,
dirent->ino, dirent->type))
return FOUND_ALL;
ctx->pos = dirent->off;
}
ff->readdir.pos = dirent->off;
ff->readdir.cache_off += reclen;
offset += reclen;
}
return res;
}
static void fuse_rdc_reset(struct inode *inode)
{
struct fuse_inode *fi = get_fuse_inode(inode);
fi->rdc.cached = false;
fi->rdc.version++;
fi->rdc.size = 0;
fi->rdc.pos = 0;
}
#define UNCACHED 1
static int fuse_readdir_cached(struct file *file, struct dir_context *ctx)
{
struct fuse_file *ff = file->private_data;
struct inode *inode = file_inode(file);
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
enum fuse_parse_result res;
pgoff_t index;
unsigned int size;
struct page *page;
void *addr;
/* Seeked? If so, reset the cache stream */
if (ff->readdir.pos != ctx->pos) {
ff->readdir.pos = 0;
ff->readdir.cache_off = 0;
}
/*
* We're just about to start reading into the cache or reading the
* cache; both cases require an up-to-date mtime value.
*/
if (!ctx->pos && fc->auto_inval_data) {
int err = fuse_update_attributes(inode, file, STATX_MTIME);
if (err)
return err;
}
retry:
spin_lock(&fi->rdc.lock);
retry_locked:
if (!fi->rdc.cached) {
/* Starting cache? Set cache mtime. */
if (!ctx->pos && !fi->rdc.size) {
fi->rdc.mtime = inode_get_mtime(inode);
fi->rdc.iversion = inode_query_iversion(inode);
}
spin_unlock(&fi->rdc.lock);
return UNCACHED;
}
/*
* When at the beginning of the directory (i.e. just after opendir(3) or
* rewinddir(3)), then need to check whether directory contents have
* changed, and reset the cache if so.
*/
if (!ctx->pos) {
struct timespec64 mtime = inode_get_mtime(inode);
if (inode_peek_iversion(inode) != fi->rdc.iversion ||
!timespec64_equal(&fi->rdc.mtime, &mtime)) {
fuse_rdc_reset(inode);
goto retry_locked;
}
}
/*
* If cache version changed since the last getdents() call, then reset
* the cache stream.
*/
if (ff->readdir.version != fi->rdc.version) {
ff->readdir.pos = 0;
ff->readdir.cache_off = 0;
}
/*
* If at the beginning of the cache, than reset version to
* current.
*/
if (ff->readdir.pos == 0)
ff->readdir.version = fi->rdc.version;
WARN_ON(fi->rdc.size < ff->readdir.cache_off);
index = ff->readdir.cache_off >> PAGE_SHIFT;
if (index == (fi->rdc.size >> PAGE_SHIFT))
size = fi->rdc.size & ~PAGE_MASK;
else
size = PAGE_SIZE;
spin_unlock(&fi->rdc.lock);
/* EOF? */
if ((ff->readdir.cache_off & ~PAGE_MASK) == size)
return 0;
page = find_get_page_flags(file->f_mapping, index,
FGP_ACCESSED | FGP_LOCK);
/* Page gone missing, then re-added to cache, but not initialized? */
if (page && !PageUptodate(page)) {
unlock_page(page);
put_page(page);
page = NULL;
}
spin_lock(&fi->rdc.lock);
if (!page) {
/*
* Uh-oh: page gone missing, cache is useless
*/
if (fi->rdc.version == ff->readdir.version)
fuse_rdc_reset(inode);
goto retry_locked;
}
/* Make sure it's still the same version after getting the page. */
if (ff->readdir.version != fi->rdc.version) {
spin_unlock(&fi->rdc.lock);
unlock_page(page);
put_page(page);
goto retry;
}
spin_unlock(&fi->rdc.lock);
/*
* Contents of the page are now protected against changing by holding
* the page lock.
*/
addr = kmap_local_page(page);
res = fuse_parse_cache(ff, addr, size, ctx);
kunmap_local(addr);
unlock_page(page);
put_page(page);
if (res == FOUND_ERR)
return -EIO;
if (res == FOUND_ALL)
return 0;
if (size == PAGE_SIZE) {
/* We hit end of page: skip to next page. */
ff->readdir.cache_off = ALIGN(ff->readdir.cache_off, PAGE_SIZE);
goto retry;
}
/*
* End of cache reached. If found position, then we are done, otherwise
* need to fall back to uncached, since the position we were looking for
* wasn't in the cache.
*/
return res == FOUND_SOME ? 0 : UNCACHED;
}
int fuse_readdir(struct file *file, struct dir_context *ctx)
{
struct fuse_file *ff = file->private_data;
struct inode *inode = file_inode(file);
int err;
if (fuse_is_bad(inode))
return -EIO;
err = UNCACHED;
if (ff->open_flags & FOPEN_CACHE_DIR)
err = fuse_readdir_cached(file, ctx);
if (err == UNCACHED)
err = fuse_readdir_uncached(file, ctx);
return err;
}
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