storage/posix: Reduce number of getxattrs for internal xattrs

Most of the gluster internal xattrs don't exceed 256 bytes. So try
getxattr with ~256 bytes. If it gives ERANGE then go the old way
of getxattr with NULL 'buf' to find the length and then getxattr with
allocated 'buf' to fill the data. This way we reduce lot of getxattrs.

 >Change-Id: I716d484bc9ba67a81d0cedb5ee3e72a5ba661f6d
 >BUG: 1265893
 >Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
 >Reviewed-on: http://review.gluster.org/12240
 >Tested-by: NetBSD Build System <jenkins@build.gluster.org>
 >Reviewed-by: N Balachandran <nbalacha@redhat.com>
 >Reviewed-by: Raghavendra Bhat <raghavendra@redhat.com>
 >(cherry picked from commit 801b7bd50a51c66e327ad79cdfc131654e069cdc)

Change-Id: I96d026e6ebee0111185c1d0a33e10a6d6577fbe7
BUG: 1267823
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/12270
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

1 files changed, 53 insertions, 4 deletions

diff --git a/xlators/storage/posix/src/posix-helpers.c b/xlators/storage/posix/src/posix-helpers.c
index 0d81e9a644a..ec6075a8dfd 100644
--- a/xlators/storage/posix/src/posix-helpers.c
+++ b/xlators/storage/posix/src/posix-helpers.c
@@ -80,6 +80,7 @@ static char* list_xattr_ignore_xattrs[] = {
         GFID_XATTR_KEY,
         NULL
 };
+
 gf_boolean_t
 posix_special_xattr (char **pattern, char *key)
 {
@@ -120,29 +121,77 @@ posix_xattr_ignorable (char *key)
         return _is_in_array (posix_ignore_xattrs, key);
 }
 
+static gf_boolean_t
+posix_is_valid_namespace (char *key)
+{
+        static char *xattr_namespaces[] = {"trusted.", "security.", "system.",
+                                           "user.", NULL };
+        int i = 0;
+
+        for (i = 0; xattr_namespaces[i]; i++) {
+                if (strncmp (key, xattr_namespaces[i],
+                             strlen (xattr_namespaces[i])) == 0)
+                        return _gf_true;
+        }
+
+        return _gf_false;
+}
+
 static int
 _posix_xattr_get_set_from_backend (posix_xattr_filler_t *filler, char *key)
 {
         ssize_t  xattr_size = -1;
         int      ret        = 0;
-        char    *value      = NULL;
+        char     *value     = NULL;
+        char     val_buf[256] = {0};
+        gf_boolean_t have_val   = _gf_false;
 
+        if (!posix_is_valid_namespace (key)) {
+                ret = -1;
+                goto out;
+        }
+
+        /* Most of the gluster internal xattrs don't exceed 256 bytes. So try
+         * getxattr with ~256 bytes. If it gives ERANGE then go the old way
+         * of getxattr with NULL buf to find the length and then getxattr with
+         * allocated buf to fill the data. This way we reduce lot of getxattrs.
+         */
         if (filler->real_path)
-                xattr_size = sys_lgetxattr (filler->real_path, key, NULL, 0);
+                xattr_size = sys_lgetxattr (filler->real_path, key, val_buf,
+                                            sizeof (val_buf) - 1);
         else
+                xattr_size = sys_fgetxattr (filler->fdnum, key, val_buf,
+                                            sizeof (val_buf) - 1);
+
+        if (xattr_size >= 0) {
+                have_val = _gf_true;
+        } else if (xattr_size == -1 && errno != ERANGE) {
+                ret = -1;
+                goto out;
+        }
+
+        if (have_val) {
+                /*No need to do getxattr*/
+        } else if (filler->real_path) {
+                xattr_size = sys_lgetxattr (filler->real_path, key, NULL, 0);
+        } else {
                 xattr_size = sys_fgetxattr (filler->fdnum, key, NULL, 0);
+        }
 
         if (xattr_size != -1) {
                 value = GF_CALLOC (1, xattr_size + 1, gf_posix_mt_char);
                 if (!value)
                         goto out;
 
-                if (filler->real_path)
+                if (have_val) {
+                        memcpy (value, val_buf, xattr_size);
+                } else if (filler->real_path) {
                         xattr_size = sys_lgetxattr (filler->real_path, key,
                                                     value, xattr_size);
-                else
+                } else {
                         xattr_size = sys_fgetxattr (filler->fdnum, key, value,
                                                     xattr_size);
+                }
                 if (xattr_size == -1) {
                         if (filler->real_path)
                                 gf_msg (filler->this->name, GF_LOG_WARNING, 0,