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-rw-r--r--fs/fuse/readdir.c604
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..f40bc51fa
--- /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_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,
+ 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, 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->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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-18 17:31:31 +0000