Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 604 insertions, 0 deletions

diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
new file mode 100644
index 000000000..14e99ffa5
--- /dev/null
+++ b/fs/fuse/readdir.c
@@ -0,0 +1,604 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2018  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/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_atomic(page);
+	if (!offset) {
+		clear_page(addr);
+		SetPageUptodate(page);
+	}
+	memcpy(addr + offset, dirent, reclen);
+	kunmap_atomic(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,
+				       entry_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, entry_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);
+
+		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->i_mtime;
+			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) {
+		if (inode_peek_iversion(inode) != fi->rdc.iversion ||
+		    !timespec64_equal(&fi->rdc.mtime, &inode->i_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(page);
+	res = fuse_parse_cache(ff, addr, size, ctx);
+	kunmap(page);
+	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;
+
+	mutex_lock(&ff->readdir.lock);
+
+	err = UNCACHED;
+	if (ff->open_flags & FOPEN_CACHE_DIR)
+		err = fuse_readdir_cached(file, ctx);
+	if (err == UNCACHED)
+		err = fuse_readdir_uncached(file, ctx);
+
+	mutex_unlock(&ff->readdir.lock);
+
+	return err;
+}