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authorVadim Lobanov <vlobanov@speakeasy.net>2006-12-10 02:21:12 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-10 09:57:22 -0800
commitbbea9f69668a3d0cf9feba15a724cd02896f8675 (patch)
treebc58506e4daba4a04309181a5501ae4eb5424783 /kernel/fork.c
parentf3d19c90fb117a5f080310a4592929aa8e1ad8e9 (diff)
[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>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c24
1 files changed, 6 insertions, 18 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 30eab4f063cd..aba595424f78 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -614,7 +614,7 @@ static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
static int count_open_files(struct fdtable *fdt)
{
- int size = fdt->max_fdset;
+ int size = fdt->max_fds;
int i;
/* Find the last open fd */
@@ -641,7 +641,6 @@ static struct files_struct *alloc_files(void)
newf->next_fd = 0;
fdt = &newf->fdtab;
fdt->max_fds = NR_OPEN_DEFAULT;
- fdt->max_fdset = EMBEDDED_FD_SET_SIZE;
fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
fdt->open_fds = (fd_set *)&newf->open_fds_init;
fdt->fd = &newf->fd_array[0];
@@ -662,7 +661,7 @@ static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
{
struct files_struct *newf;
struct file **old_fds, **new_fds;
- int open_files, size, i, expand;
+ int open_files, size, i;
struct fdtable *old_fdt, *new_fdt;
*errorp = -ENOMEM;
@@ -673,25 +672,14 @@ static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
spin_lock(&oldf->file_lock);
old_fdt = files_fdtable(oldf);
new_fdt = files_fdtable(newf);
- size = old_fdt->max_fdset;
open_files = count_open_files(old_fdt);
- expand = 0;
/*
- * Check whether we need to allocate a larger fd array or fd set.
- * Note: we're not a clone task, so the open count won't change.
+ * Check whether we need to allocate a larger fd array and fd set.
+ * Note: we're not a clone task, so the open count won't change.
*/
- if (open_files > new_fdt->max_fdset) {
- new_fdt->max_fdset = 0;
- expand = 1;
- }
if (open_files > new_fdt->max_fds) {
new_fdt->max_fds = 0;
- expand = 1;
- }
-
- /* if the old fdset gets grown now, we'll only copy up to "size" fds */
- if (expand) {
spin_unlock(&oldf->file_lock);
spin_lock(&newf->file_lock);
*errorp = expand_files(newf, open_files-1);
@@ -739,8 +727,8 @@ static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
/* This is long word aligned thus could use a optimized version */
memset(new_fds, 0, size);
- if (new_fdt->max_fdset > open_files) {
- int left = (new_fdt->max_fdset-open_files)/8;
+ if (new_fdt->max_fds > open_files) {
+ int left = (new_fdt->max_fds-open_files)/8;
int start = open_files / (8 * sizeof(unsigned long));
memset(&new_fdt->open_fds->fds_bits[start], 0, left);