p71924506
/
linux_old1
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

fuse: only reuse auxiliary request in fuse_writepage_in_flight() 

Don't reuse the queued request, even if it only contains a single page.
This is needed because previous locking changes (spliting out
fiq->waitq.lock from fc->lock) broke the assumption that request will
remain in FR_PENDING at least until the new page contents are copied.

This fix removes a slight optimization for a rare corner case, so we really
shoudln't care.

Reported-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Fixes: fd22d62ed0 ("fuse: no fc->lock for iqueue parts")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2019-01-16 10:27:59 +01:00
parent 7f305ca192
commit 419234d595
1 changed files with 7 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
fs/fuse/file.c
View File

@ -1746,9 +1746,9 @@ static void fuse_writepages_send(struct fuse_fill_wb_data *data)
/*
* First recheck under fi->lock if the offending offset is still under
* writeback. If yes, then iterate write requests, to see if there's one
* already added for a page at this offset. If there's none, then insert this
* new request onto the auxiliary list, otherwise reuse the existing one by
* writeback. If yes, then iterate auxiliary write requests, to see if there's
* one already added for a page at this offset. If there's none, then insert
* this new request onto the auxiliary list, otherwise reuse the existing one by
* copying the new page contents over to the old temporary page.
*/
static bool fuse_writepage_in_flight(struct fuse_req *new_req,
@ -1771,13 +1771,14 @@ static bool fuse_writepage_in_flight(struct fuse_req *new_req,
}
new_req->num_pages = 1;
for (tmp = old_req; tmp != NULL; tmp = tmp->misc.write.next) {
for (tmp = old_req->misc.write.next; tmp; tmp = tmp->misc.write.next) {
pgoff_t curr_index;
WARN_ON(tmp->inode != new_req->inode);
curr_index = tmp->misc.write.in.offset >> PAGE_SHIFT;
if (tmp->num_pages == 1 && curr_index == page->index &&
test_bit(FR_PENDING, &tmp->flags)) {
if (curr_index == page->index) {
WARN_ON(tmp->num_pages != 1);
WARN_ON(!test_bit(FR_PENDING, &tmp->flags));
copy_highpage(tmp->pages[0], page);
break;
}