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vmas: Don't call stat on vm file twice

Browse source 
When parsing mappings in proc, we fstat vm file, later,
when dumping it, we stat it again to fill fd_parms.
The 2nd stat is not required, we can keep the stat in
vma_area.

This removed 35% of all stat calls on dump of basic container.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Pavel Emelyanov 2014-02-03 00:18:32 +04:00
parent bd7bf7bd39
commit 608db864a3
3 changed files with 21 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

15
cr-dump.c
View file

@ -128,6 +128,8 @@ void free_mappings(struct vm_area_list *vma_area_list)
list_for_each_entry_safe(vma_area, p, &vma_area_list->h, list) {
close_vma_file(vma_area);
if (!vma_area->file_borrowed)
free(vma_area->st);
free(vma_area);
}
@ -341,15 +343,14 @@ static int dump_task_rlims(int pid, struct cr_fdset *fds)
return 0;
}
static int dump_filemap(pid_t pid, VmaEntry *vma, int file_fd,
static int dump_filemap(pid_t pid, struct vma_area *vma_area,
const struct cr_fdset *fdset)
{
struct fd_parms p = FD_PARMS_INIT;
VmaEntry *vma = &vma_area->vma;
if (fstat(file_fd, &p.stat) < 0) {
pr_perror("Can't stat file for vma");
return -1;
}
BUG_ON(!vma_area->st);
p.stat = *vma_area->st;
if ((vma->prot & PROT_WRITE) && vma_entry_is(vma, VMA_FILE_SHARED))
p.flags = O_RDWR;
@ -357,7 +358,7 @@ static int dump_filemap(pid_t pid, VmaEntry *vma, int file_fd,
p.flags = O_RDONLY;
vma->shmid = fd_id_generate_special();
return dump_one_reg_file(file_fd, vma->shmid, &p);
return dump_one_reg_file(vma_area->vm_file_fd, vma->shmid, &p);
}
static int check_sysvipc_map_dump(pid_t pid, VmaEntry *vma)
@ -395,7 +396,7 @@ static int dump_task_mappings(pid_t pid, const struct vm_area_list *vma_area_lis
ret = add_shmem_area(pid, vma);
else if (vma_entry_is(vma, VMA_FILE_PRIVATE) ||
vma_entry_is(vma, VMA_FILE_SHARED))
ret = dump_filemap(pid, vma, vma_area->vm_file_fd, cr_fdset);
ret = dump_filemap(pid, vma_area, cr_fdset);
else if (vma_entry_is(vma, VMA_AREA_SOCKET))
ret = dump_socket_map(vma_area);
else

2
include/vma.h
View file

@ -27,6 +27,8 @@ struct vma_area {
unsigned long premmaped_addr;
bool file_borrowed;
struct stat *st;
};
extern int collect_mappings(pid_t pid, struct vm_area_list *vma_area_list);

17
proc_parse.c
View file

@ -351,16 +351,21 @@ int parse_smaps(pid_t pid, struct vm_area_list *vma_area_list, bool use_map_file
vma_area->vma.flags |= (prev->vma.flags & MAP_ANONYMOUS);
vma_area->vma.status = prev->vma.status;
vma_area->vma.shmid = prev->vma.shmid;
vma_area->st = prev->st;
} else if (vma_area->vm_file_fd >= 0) {
struct stat st_buf;
struct stat *st_buf;
if (fstat(vma_area->vm_file_fd, &st_buf) < 0) {
st_buf = vma_area->st = xmalloc(sizeof(*st_buf));
if (!st_buf)
goto err;
if (fstat(vma_area->vm_file_fd, st_buf) < 0) {
pr_perror("Failed fstat on %d's map %lu", pid, start);
goto err;
}
if (!S_ISREG(st_buf.st_mode) &&
!(S_ISCHR(st_buf.st_mode) && st_buf.st_rdev == DEVZERO)) {
if (!S_ISREG(st_buf->st_mode) &&
!(S_ISCHR(st_buf->st_mode) && st_buf->st_rdev == DEVZERO)) {
pr_err("Can't handle non-regular mapping on %d's map %lu\n", pid, start);
goto err;
}
@ -369,12 +374,12 @@ int parse_smaps(pid_t pid, struct vm_area_list *vma_area_list, bool use_map_file
* /dev/zero stands for anon-shared mapping
* otherwise it's some file mapping.
*/
if (is_anon_shmem_map(st_buf.st_dev)) {
if (is_anon_shmem_map(st_buf->st_dev)) {
if (!(vma_area->vma.flags & MAP_SHARED))
goto err_bogus_mapping;
vma_area->vma.flags |= MAP_ANONYMOUS;
vma_area->vma.status |= VMA_ANON_SHARED;
vma_area->vma.shmid = st_buf.st_ino;
vma_area->vma.shmid = st_buf->st_ino;
if (!strcmp(file_path, "/SYSV")) {
pr_info("path: %s\n", file_path);