Re: [PATCH] uevent_can_discard: optimize devpath check

[<tang.junhui@zte.com.cn>]

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It  looks fine to me.




Regards,

Tang Junhui




＞ This uses roughly 10% cycles of the sscanf-based implementation.

＞ 

＞ Improves: ee8888f0 "multipath-tools: improve processing efficiency..."

＞ Signed-off-by: Martin Wilck ＜mwilck@suse.com＞

＞ ---

＞  libmultipath/uevent.c | 37 +++++++++++++++++++++++--------------

＞  1 file changed, 23 insertions(+), 14 deletions(-)

＞ 

＞ diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c

＞ index 6e2527bd..367e129a 100644

＞ --- a/libmultipath/uevent.c

＞ +++ b/libmultipath/uevent.c

＞ @@ -143,26 +143,35 @@ uevent_need_merge(void)

＞      return need_merge

＞  }

＞  

＞ +static bool

＞ +uevent_can_discard_by_devpath(const char *devpath)

＞ +{

＞ +    static const char BLOCK[] = "/block/"

＞ +    const char *tmp = strstr(devpath, BLOCK)

＞ +

＞ +    if (tmp == NULL) {

＞ +        condlog(4, "no /block/ in '%s'", devpath)

＞ +        return true

＞ +    }

＞ +    tmp += sizeof(BLOCK) - 1

＞ +    if (*tmp == '\0')

＞ +        /* just ".../block/" - discard */

＞ +        return true

＞ +    /*

＞ +     * If there are more path elements after ".../block/xyz",

＞ +     * it's a partition - discard it but don't discard ".../block/sda/".

＞ +     */

＞ +    tmp = strchr(tmp, '/')

＞ +    return tmp != NULL && *(tmp + 1) != '\0'

＞ +}

＞ +

＞  bool

＞  uevent_can_discard(struct uevent *uev)

＞  {

＞ -    char *tmp

＞ -    char a[11], b[11]

＞      struct config * conf

＞  

＞ -    /*

＞ -     * keep only block devices, discard partitions

＞ -     */

＞ -    tmp = strstr(uev-＞devpath, "/block/")

＞ -    if (tmp == NULL){

＞ -        condlog(4, "no /block/ in '%s'", uev-＞devpath)

＞ +    if (uevent_can_discard_by_devpath(uev-＞devpath))

＞          return true

＞ -    }

＞ -    if (sscanf(tmp, "/block/%10s", a) != 1 ||

＞ -        sscanf(tmp, "/block/%10[^/]/%10s", a, b) == 2) {

＞ -        condlog(4, "discard event on %s", uev-＞devpath)

＞ -        return true

＞ -    }

＞  

＞      /* 

＞       * do not filter dm devices by devnode

＞ -- 

＞ 2.12.0

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