From: Prasanna Meda <pmeda@akamai.com>
Third version:
Seek fix: When last_addr is reset by lseek, we need to depend on f_pos and
ignore f_version here. This is fixed and made this code common with starting map.
Signed-off-by: Prasanna Meda <pmeda@akamai.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/fs/proc/task_mmu.c | 24 ++++++++++++------------
1 files changed, 12 insertions(+), 12 deletions(-)
diff -puN fs/proc/task_mmu.c~speedup-proc-pid-maps-fix-fix fs/proc/task_mmu.c
--- 25/fs/proc/task_mmu.c~speedup-proc-pid-maps-fix-fix 2005-01-09 23:58:18.735615832 -0800
+++ 25-akpm/fs/proc/task_mmu.c 2005-01-09 23:58:18.738615376 -0800
@@ -121,6 +121,13 @@ static void *m_start(struct seq_file *m,
struct vm_area_struct *map, *tail_map;
loff_t l = *pos;
+ /*
+ * We remember last_addr rather than next_addr to hit with
+ * mmap_cache most of the time. We have zero last_addr at
+ * the begining and also after lseek. We will have -1 last_addr
+ * after the end of the maps.
+ */
+
if (last_addr == -1UL)
return NULL;
@@ -133,23 +140,16 @@ static void *m_start(struct seq_file *m,
tail_map = get_gate_vma(task);
down_read(&mm->mmap_sem);
- /*
- * First map is special, since we remember last_addr
- * rather than current_addr to hit with mmap_cache most of the time.
- */
- if (!l) {
- map = mm->mmap;
- goto out;
- }
-
/* Start with last addr hint */
- map = find_vma(mm, last_addr);
- if (map) {
+ if (last_addr && (map = find_vma(mm, last_addr))) {
map = map->vm_next;
goto out;
}
- /* Check the map index is within the range, and do linear scan */
+ /*
+ * Check the map index is within the range and do
+ * sequential scan until f_pos.
+ */
if ((unsigned long)l < mm->map_count) {
map = mm->mmap;
while (l-- && map)
_