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dev-cache: skip double stat() call on each _insert

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When the device is inserted in dev_name_confirmed() stat() is
called twice as _insert() has it's own stat() call.

Extend _insert() parameter with struct stat* - which could be used
if it has been just obtained.  When NULL is passed code is
doing its own stat() call as before.
This commit is contained in:
Zdenek Kabelac 2011-11-25 10:01:37 +01:00
parent 7c5feaed3b
commit 6c0e44d5a2
2 changed files with 32 additions and 18 deletions
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1
WHATS_NEW
View File

@ -1,5 +1,6 @@
Version 2.02.105 -
=====================================
Optimize double call of stat() for cached devices.
Enable support for thin provisioning for default configuration.
Improve process_each_lv_in_vg() tag processing.
Reodered and simplified logging code.

45
lib/device/dev-cache.c
View File

@ -50,7 +50,8 @@ static struct {
#define _free(x) dm_pool_free(_cache.mem, (x))
#define _strdup(x) dm_pool_strdup(_cache.mem, (x))
static int _insert(const char *path, int rec, int check_with_udev_db);
static int _insert(const char *path, const struct stat *info,
int rec, int check_with_udev_db);
/* Setup non-zero members of passed zeroed 'struct device' */
static void _dev_init(struct device *dev, int max_error_count)
@ -442,7 +443,7 @@ static int _insert_dir(const char *dir)
return_0;
_collapse_slashes(path);
r &= _insert(path, 1, 0);
r &= _insert(path, NULL, 1, 0);
dm_free(path);
free(dirent[n]);
@ -528,14 +529,14 @@ static int _insert_udev_dir(struct udev *udev, const char *dir)
log_very_verbose("udev failed to return a device node for entry %s.",
entry_name);
else
r &= _insert(node_name, 0, 0);
r &= _insert(node_name, NULL, 0, 0);
udev_list_entry_foreach(symlink_entry, udev_device_get_devlinks_list_entry(device)) {
if (!(symlink_name = udev_list_entry_get_name(symlink_entry)))
log_very_verbose("udev failed to return a symlink name for entry %s.",
entry_name);
else
r &= _insert(symlink_name, 0, 0);
r &= _insert(symlink_name, NULL, 0, 0);
}
udev_device_unref(device);
@ -589,28 +590,33 @@ static void _insert_dirs(struct dm_list *dirs)
#endif /* UDEV_SYNC_SUPPORT */
static int _insert(const char *path, int rec, int check_with_udev_db)
static int _insert(const char *path, const struct stat *info,
int rec, int check_with_udev_db)
{
struct stat info;
struct stat tinfo;
int r = 0;
if (stat(path, &info) < 0) {
if (!info) {
if (stat(path, &tinfo) < 0) {
log_sys_very_verbose("stat", path);
return 0;
}
info = &tinfo;
}
if (check_with_udev_db && !_device_in_udev_db(info.st_rdev)) {
if (check_with_udev_db && !_device_in_udev_db(info->st_rdev)) {
log_very_verbose("%s: Not in udev db", path);
return 0;
}
if (S_ISDIR(info.st_mode)) { /* add a directory */
if (S_ISDIR(info->st_mode)) { /* add a directory */
/* check it's not a symbolic link */
if (lstat(path, &info) < 0) {
if (lstat(path, &tinfo) < 0) {
log_sys_very_verbose("lstat", path);
return 0;
}
if (S_ISLNK(info.st_mode)) {
if (S_ISLNK(tinfo.st_mode)) {
log_debug_devs("%s: Symbolic link to directory", path);
return 1;
}
@ -618,12 +624,12 @@ static int _insert(const char *path, int rec, int check_with_udev_db)
if (rec && !_insert_dir(path))
return_0;
} else { /* add a device */
if (!S_ISBLK(info.st_mode)) {
if (!S_ISBLK(info->st_mode)) {
log_debug_devs("%s: Not a block device", path);
return 1;
}
if (!_insert_dev(path, info.st_rdev))
if (!_insert_dev(path, info->st_rdev))
return_0;
}
@ -881,7 +887,7 @@ const char *dev_name_confirmed(struct device *dev, int quiet)
if (dm_list_size(&dev->aliases) > 1) {
dm_list_del(dev->aliases.n);
if (!r)
_insert(name, 0, obtain_device_list_from_udev());
_insert(name, &buf, 0, obtain_device_list_from_udev());
continue;
}
@ -903,13 +909,20 @@ struct device *dev_cache_get(const char *name, struct dev_filter *f)
return d;
/* If the entry's wrong, remove it */
if (d && (stat(name, &buf) || (buf.st_rdev != d->dev))) {
if (stat(name, &buf) < 0) {
if (d)
dm_hash_remove(_cache.names, name);
log_sys_very_verbose("stat", name);
return NULL;
}
if (d && (buf.st_rdev != d->dev)) {
dm_hash_remove(_cache.names, name);
d = NULL;
}
if (!d) {
_insert(name, 0, obtain_device_list_from_udev());
_insert(name, &buf, 0, obtain_device_list_from_udev());
d = (struct device *) dm_hash_lookup(_cache.names, name);
if (!d) {
_full_scan(0);