fuse: fix warning in tree_insert() and clean up writepage insertion
fuse_writepages_fill() calls tree_insert() with ap->num_pages = 0 which
triggers the following warning:
WARNING: CPU: 1 PID: 17211 at fs/fuse/file.c:1728 tree_insert+0xab/0xc0 [fuse]
RIP: 0010:tree_insert+0xab/0xc0 [fuse]
Call Trace:
fuse_writepages_fill+0x5da/0x6a0 [fuse]
write_cache_pages+0x171/0x470
fuse_writepages+0x8a/0x100 [fuse]
do_writepages+0x43/0xe0
Fix up the warning and clean up the code around rb-tree insertion:
- Rename tree_insert() to fuse_insert_writeback() and make it return the
conflicting entry in case of failure
- Re-add tree_insert() as a wrapper around fuse_insert_writeback()
- Rename fuse_writepage_in_flight() to fuse_writepage_add() and reverse
the meaning of the return value to mean
+ "true" in case the writepage entry was successfully added
+ "false" in case it was in-fligt queued on an existing writepage
entry's auxiliary list or the existing writepage entry's temporary
page updated
Switch from fuse_find_writeback() + tree_insert() to
fuse_insert_writeback()
- Move setting orig_pages to before inserting/updating the entry; this may
result in the orig_pages value being discarded later in case of an
in-flight request
- In case of a new writepage entry use fuse_writepage_add()
unconditionally, only set data->wpa if the entry was added.
Fixes: 6b2fb79963
("fuse: optimize writepages search")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Original-path-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
parent
69a6487ac0
commit
c146024ec4
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@ -1674,7 +1674,8 @@ __acquires(fi->lock)
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}
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}
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static void tree_insert(struct rb_root *root, struct fuse_writepage_args *wpa)
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static struct fuse_writepage_args *fuse_insert_writeback(struct rb_root *root,
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struct fuse_writepage_args *wpa)
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{
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pgoff_t idx_from = wpa->ia.write.in.offset >> PAGE_SHIFT;
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pgoff_t idx_to = idx_from + wpa->ia.ap.num_pages - 1;
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@ -1697,11 +1698,17 @@ static void tree_insert(struct rb_root *root, struct fuse_writepage_args *wpa)
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else if (idx_to < curr_index)
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p = &(*p)->rb_left;
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else
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return (void) WARN_ON(true);
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return curr;
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}
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rb_link_node(&wpa->writepages_entry, parent, p);
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rb_insert_color(&wpa->writepages_entry, root);
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return NULL;
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}
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static void tree_insert(struct rb_root *root, struct fuse_writepage_args *wpa)
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{
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WARN_ON(fuse_insert_writeback(root, wpa));
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}
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static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_args *args,
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@ -1953,14 +1960,14 @@ static void fuse_writepages_send(struct fuse_fill_wb_data *data)
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}
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/*
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* First recheck under fi->lock if the offending offset is still under
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* writeback. If yes, then iterate auxiliary write requests, to see if there's
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* Check under fi->lock if the page is under writeback, and insert it onto the
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* rb_tree if not. Otherwise iterate auxiliary write requests, to see if there's
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* one already added for a page at this offset. If there's none, then insert
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* this new request onto the auxiliary list, otherwise reuse the existing one by
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* copying the new page contents over to the old temporary page.
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* swapping the new temp page with the old one.
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*/
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static bool fuse_writepage_in_flight(struct fuse_writepage_args *new_wpa,
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struct page *page)
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static bool fuse_writepage_add(struct fuse_writepage_args *new_wpa,
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struct page *page)
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{
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struct fuse_inode *fi = get_fuse_inode(new_wpa->inode);
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struct fuse_writepage_args *tmp;
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@ -1968,17 +1975,15 @@ static bool fuse_writepage_in_flight(struct fuse_writepage_args *new_wpa,
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struct fuse_args_pages *new_ap = &new_wpa->ia.ap;
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WARN_ON(new_ap->num_pages != 0);
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new_ap->num_pages = 1;
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spin_lock(&fi->lock);
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rb_erase(&new_wpa->writepages_entry, &fi->writepages);
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old_wpa = fuse_find_writeback(fi, page->index, page->index);
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old_wpa = fuse_insert_writeback(&fi->writepages, new_wpa);
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if (!old_wpa) {
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tree_insert(&fi->writepages, new_wpa);
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spin_unlock(&fi->lock);
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return false;
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return true;
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}
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new_ap->num_pages = 1;
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for (tmp = old_wpa->next; tmp; tmp = tmp->next) {
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pgoff_t curr_index;
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@ -2007,7 +2012,7 @@ static bool fuse_writepage_in_flight(struct fuse_writepage_args *new_wpa,
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fuse_writepage_free(new_wpa);
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}
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return true;
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return false;
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}
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static int fuse_writepages_fill(struct page *page,
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@ -2086,12 +2091,6 @@ static int fuse_writepages_fill(struct page *page,
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ap->args.end = fuse_writepage_end;
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ap->num_pages = 0;
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wpa->inode = inode;
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spin_lock(&fi->lock);
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tree_insert(&fi->writepages, wpa);
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spin_unlock(&fi->lock);
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data->wpa = wpa;
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}
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set_page_writeback(page);
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@ -2099,26 +2098,25 @@ static int fuse_writepages_fill(struct page *page,
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ap->pages[ap->num_pages] = tmp_page;
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ap->descs[ap->num_pages].offset = 0;
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ap->descs[ap->num_pages].length = PAGE_SIZE;
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data->orig_pages[ap->num_pages] = page;
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inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
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inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
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err = 0;
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if (is_writeback && fuse_writepage_in_flight(wpa, page)) {
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if (data->wpa) {
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/*
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* Protected by fi->lock against concurrent access by
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* fuse_page_is_writeback().
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*/
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spin_lock(&fi->lock);
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ap->num_pages++;
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spin_unlock(&fi->lock);
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} else if (fuse_writepage_add(wpa, page)) {
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data->wpa = wpa;
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} else {
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end_page_writeback(page);
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data->wpa = NULL;
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goto out_unlock;
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}
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data->orig_pages[ap->num_pages] = page;
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/*
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* Protected by fi->lock against concurrent access by
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* fuse_page_is_writeback().
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*/
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spin_lock(&fi->lock);
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ap->num_pages++;
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spin_unlock(&fi->lock);
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out_unlock:
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unlock_page(page);
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