[PATCH] fdtable: Make fdarray and fdsets equal in size

Currently, each fdtable supports three dynamically-sized arrays of data: the
fdarray and two fdsets.  The code allows the number of fds supported by the
fdarray (fdtable->max_fds) to differ from the number of fds supported by each
of the fdsets (fdtable->max_fdset).

In practice, it is wasteful for these two sizes to differ: whenever we hit a
limit on the smaller-capacity structure, we will reallocate the entire fdtable
and all the dynamic arrays within it, so any delta in the memory used by the
larger-capacity structure will never be touched at all.

Rather than hogging this excess, we shouldn't even allocate it in the first
place, and keep the capacities of the fdarray and the fdsets equal.  This
patch removes fdtable->max_fdset.  As an added bonus, most of the supporting
code becomes simpler.

Signed-off-by: Vadim Lobanov <vlobanov@speakeasy.net>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 0 insertions, 7 deletions

diff --git a/include/linux/file.h b/include/linux/file.h
index 6e77b9177f9e..02be4012225b 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -26,14 +26,8 @@ struct embedded_fd_set {
         unsigned long fds_bits[1];
 };
 
-/*
- * More than this number of fds: we use a separately allocated fd_set
- */
-#define EMBEDDED_FD_SET_SIZE (BITS_PER_BYTE * sizeof(struct embedded_fd_set))
-
 struct fdtable {
         unsigned int max_fds;
-        int max_fdset;
         struct file ** fd;      /* current fd array */
         fd_set *close_on_exec;
         fd_set *open_fds;
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 7272ff9ee77c..58c18daab65d 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -12,7 +12,6 @@
 #define INIT_FDTABLE \
 {                                                       \
         .max_fds        = NR_OPEN_DEFAULT,              \
-        .max_fdset      = EMBEDDED_FD_SET_SIZE,         \
         .fd             = &init_files.fd_array[0],      \
         .close_on_exec  = (fd_set *)&init_files.close_on_exec_init, \
         .open_fds       = (fd_set *)&init_files.open_fds_init,  \