1 files changed, 8 insertions, 4 deletions

diff --git a/fs/open.c b/fs/open.c
index 70e0230d8e77..7d02d19bd0a2 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -890,6 +890,10 @@ EXPORT_SYMBOL(filp_open);
  * a fully instantiated struct file to the caller.
  * This function is meant to be called from within a filesystem's
  * lookup method.
+ * Beware of calling it for non-regular files! Those ->open methods might block
+ * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
+ * leading to a deadlock, as nobody can open that fifo anymore, because
+ * another process to open fifo will block on locked parent when doing lookup).
  * Note that in case of error, nd->intent.open.file is destroyed, but the
  * path information remains valid.
  * If the open callback is set to NULL, then the standard f_op->open()
@@ -973,7 +977,7 @@ repeat:
         fdt = files_fdtable(files);
         fd = find_next_zero_bit(fdt->open_fds->fds_bits,
                                 fdt->max_fdset,
-                                fdt->next_fd);
+                                files->next_fd);
 
         /*
          * N.B. For clone tasks sharing a files structure, this test
@@ -998,7 +1002,7 @@ repeat:
 
         FD_SET(fd, fdt->open_fds);
         FD_CLR(fd, fdt->close_on_exec);
-        fdt->next_fd = fd + 1;
+        files->next_fd = fd + 1;
 #if 1
         /* Sanity check */
         if (fdt->fd[fd] != NULL) {
@@ -1019,8 +1023,8 @@ static void __put_unused_fd(struct files_struct *files, unsigned int fd)
 {
         struct fdtable *fdt = files_fdtable(files);
         __FD_CLR(fd, fdt->open_fds);
-        if (fd < fdt->next_fd)
-                fdt->next_fd = fd;
+        if (fd < files->next_fd)
+                files->next_fd = fd;
 }
 
 void fastcall put_unused_fd(unsigned int fd)