storage: reduce number of stat calls

We are calling fstat() at least twice per storage volume in
a directory storage pool; this is rather wasteful.  Refactoring
this is also a step towards making code reusable for gluster,
where gluster can provide struct stat but cannot use fstat().

* src/storage/storage_backend.h
(virStorageBackendVolOpenCheckMode)
(virStorageBackendUpdateVolTargetInfoFD): Update signature.
* src/storage/storage_backend.c
(virStorageBackendVolOpenCheckMode): Pass stat results back.
(virStorageBackendUpdateVolTargetInfoFD): Use existing stats.
(virStorageBackendVolOpen, virStorageBackendUpdateVolTargetInfo):
Update callers.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Likewise.
* src/storage/storage_backend_scsi.c
(virStorageBackendSCSIUpdateVolTargetInfo): Likewise.
* src/storage/storage_backend_mpath.c
(virStorageBackendMpathUpdateVolTargetInfo): Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
index aa2ed283acc981d76e5c18d7f148277e2230c280..4b1b00db1157c6e5411236569c879fecce9b11c4 100644 (file)
--- a/src/storage/storage_backend.c
+++ b/src/storage/storage_backend.c
@@ -1152,30 +1152,30 @@ virStorageBackendForType(int type)
  * volume is a dangling symbolic link.
  */
 int
-virStorageBackendVolOpenCheckMode(const char *path, unsigned int flags)
+virStorageBackendVolOpenCheckMode(const char *path, struct stat *sb,
+                                  unsigned int flags)
 {
     int fd, mode = 0;
-    struct stat sb;
     char *base = last_component(path);
 
-    if (lstat(path, &sb) < 0) {
+    if (lstat(path, sb) < 0) {
         virReportSystemError(errno,
                              _("cannot stat file '%s'"),
                              path);
         return -1;
     }
 
-    if (S_ISFIFO(sb.st_mode)) {
+    if (S_ISFIFO(sb->st_mode)) {
         VIR_WARN("ignoring FIFO '%s'", path);
         return -2;
-    } else if (S_ISSOCK(sb.st_mode)) {
+    } else if (S_ISSOCK(sb->st_mode)) {
         VIR_WARN("ignoring socket '%s'", path);
         return -2;
     }
 
     if ((fd = open(path, O_RDONLY|O_NONBLOCK|O_NOCTTY)) < 0) {
         if ((errno == ENOENT || errno == ELOOP) &&
-            S_ISLNK(sb.st_mode)) {
+            S_ISLNK(sb->st_mode)) {
             VIR_WARN("ignoring dangling symlink '%s'", path);
             return -2;
         }
@@ -1186,7 +1186,7 @@ virStorageBackendVolOpenCheckMode(const char *path, unsigned int flags)
         return -1;
     }
 
-    if (fstat(fd, &sb) < 0) {
+    if (fstat(fd, sb) < 0) {
         virReportSystemError(errno,
                              _("cannot stat file '%s'"),
                              path);
@@ -1194,13 +1194,13 @@ virStorageBackendVolOpenCheckMode(const char *path, unsigned int flags)
         return -1;
     }
 
-    if (S_ISREG(sb.st_mode))
+    if (S_ISREG(sb->st_mode))
         mode = VIR_STORAGE_VOL_OPEN_REG;
-    else if (S_ISCHR(sb.st_mode))
+    else if (S_ISCHR(sb->st_mode))
         mode = VIR_STORAGE_VOL_OPEN_CHAR;
-    else if (S_ISBLK(sb.st_mode))
+    else if (S_ISBLK(sb->st_mode))
         mode = VIR_STORAGE_VOL_OPEN_BLOCK;
-    else if (S_ISDIR(sb.st_mode)) {
+    else if (S_ISDIR(sb->st_mode)) {
         mode = VIR_STORAGE_VOL_OPEN_DIR;
 
         if (STREQ(base, ".") ||
@@ -1229,7 +1229,8 @@ virStorageBackendVolOpenCheckMode(const char *path, unsigned int flags)
 
 int virStorageBackendVolOpen(const char *path)
 {
-    return virStorageBackendVolOpenCheckMode(path,
+    struct stat sb;
+    return virStorageBackendVolOpenCheckMode(path, &sb,
                                              VIR_STORAGE_VOL_OPEN_DEFAULT);
 }
 
@@ -1240,14 +1241,16 @@ virStorageBackendUpdateVolTargetInfo(virStorageVolTargetPtr target,
                                      unsigned int openflags)
 {
     int ret, fd;
+    struct stat sb;
 
-    if ((ret = virStorageBackendVolOpenCheckMode(target->path,
+    if ((ret = virStorageBackendVolOpenCheckMode(target->path, &sb,
                                                  openflags)) < 0)
         return ret;
 
     fd = ret;
     ret = virStorageBackendUpdateVolTargetInfoFD(target,
                                                  fd,
+                                                 &sb,
                                                  allocation,
                                                  capacity);
 
@@ -1298,35 +1301,28 @@ int virStorageBackendUpdateVolInfo(virStorageVolDefPtr vol,
 int
 virStorageBackendUpdateVolTargetInfoFD(virStorageVolTargetPtr target,
                                        int fd,
+                                       struct stat *sb,
                                        unsigned long long *allocation,
                                        unsigned long long *capacity)
 {
-    struct stat sb;
 #if WITH_SELINUX
     security_context_t filecon = NULL;
 #endif
 
-    if (fstat(fd, &sb) < 0) {
-        virReportSystemError(errno,
-                             _("cannot stat file '%s'"),
-                             target->path);
-        return -1;
-    }
-
     if (allocation) {
-        if (S_ISREG(sb.st_mode)) {
+        if (S_ISREG(sb->st_mode)) {
 #ifndef WIN32
-            *allocation = (unsigned long long)sb.st_blocks *
+            *allocation = (unsigned long long)sb->st_blocks *
                           (unsigned long long)DEV_BSIZE;
 #else
-            *allocation = sb.st_size;
+            *allocation = sb->st_size;
 #endif
             /* Regular files may be sparse, so logical size (capacity) is not same
              * as actual allocation above
              */
             if (capacity)
-                *capacity = sb.st_size;
-        } else if (S_ISDIR(sb.st_mode)) {
+                *capacity = sb->st_size;
+        } else if (S_ISDIR(sb->st_mode)) {
             *allocation = 0;
             if (capacity)
                 *capacity = 0;
@@ -1351,16 +1347,16 @@ virStorageBackendUpdateVolTargetInfoFD(virStorageVolTargetPtr target,
         }
     }
 
-    target->perms.mode = sb.st_mode & S_IRWXUGO;
-    target->perms.uid = sb.st_uid;
-    target->perms.gid = sb.st_gid;
+    target->perms.mode = sb->st_mode & S_IRWXUGO;
+    target->perms.uid = sb->st_uid;
+    target->perms.gid = sb->st_gid;
 
     if (!target->timestamps && VIR_ALLOC(target->timestamps) < 0)
         return -1;
-    target->timestamps->atime = get_stat_atime(&sb);
-    target->timestamps->btime = get_stat_birthtime(&sb);
-    target->timestamps->ctime = get_stat_ctime(&sb);
-    target->timestamps->mtime = get_stat_mtime(&sb);
+    target->timestamps->atime = get_stat_atime(sb);
+    target->timestamps->btime = get_stat_birthtime(sb);
+    target->timestamps->ctime = get_stat_ctime(sb);
+    target->timestamps->mtime = get_stat_mtime(sb);
 
     VIR_FREE(target->perms.label);
 

diff --git a/src/storage/storage_backend.h b/src/storage/storage_backend.h
index 3dc9c64a14c725e91ae511c7753c1190c5fd8e1f..d8d3097283343fd5b943d1be224f26d383168bbd 100644 (file)
--- a/src/storage/storage_backend.h
+++ b/src/storage/storage_backend.h
@@ -24,6 +24,8 @@
 #ifndef __VIR_STORAGE_BACKEND_H__
 # define __VIR_STORAGE_BACKEND_H__
 
+# include <sys/stat.h>
+
 # include "internal.h"
 # include "storage_conf.h"
 # include "vircommand.h"
@@ -108,9 +110,10 @@ enum {
                                        VIR_STORAGE_VOL_OPEN_CHAR     |\
                                        VIR_STORAGE_VOL_OPEN_BLOCK)
 
-int virStorageBackendVolOpenCheckMode(const char *path, unsigned int flags)
-ATTRIBUTE_RETURN_CHECK
-ATTRIBUTE_NONNULL(1);
+int virStorageBackendVolOpenCheckMode(const char *path, struct stat *sb,
+                                      unsigned int flags)
+    ATTRIBUTE_RETURN_CHECK
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
 int virStorageBackendUpdateVolInfo(virStorageVolDefPtr vol,
                                    int withCapacity);
@@ -124,6 +127,7 @@ int virStorageBackendUpdateVolTargetInfo(virStorageVolTargetPtr target,
                                          unsigned int openflags);
 int virStorageBackendUpdateVolTargetInfoFD(virStorageVolTargetPtr target,
                                            int fd,
+                                           struct stat *sb,
                                            unsigned long long *allocation,
                                            unsigned long long *capacity);
 int

diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index 7ff950b12e60b6a1f7c3ab0518a22b1e9e13733f..58fb7c1d0df362e414f2853dc88a4664aa3a6f4f 100644 (file)
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -70,18 +70,19 @@ virStorageBackendProbeTarget(virStorageVolTargetPtr target,
     int fd = -1;
     int ret = -1;
     virStorageFileMetadata *meta = NULL;
+    struct stat sb;
 
     *backingStore = NULL;
     *backingStoreFormat = VIR_STORAGE_FILE_AUTO;
     if (encryption)
         *encryption = NULL;
 
-    if ((ret = virStorageBackendVolOpenCheckMode(target->path,
+    if ((ret = virStorageBackendVolOpenCheckMode(target->path, &sb,
                                         VIR_STORAGE_VOL_FS_REFRESH_FLAGS)) < 0)
         goto error; /* Take care to propagate ret, it is not always -1 */
     fd = ret;
 
-    if ((ret = virStorageBackendUpdateVolTargetInfoFD(target, fd,
+    if ((ret = virStorageBackendUpdateVolTargetInfoFD(target, fd, &sb,
                                                       allocation,
                                                       capacity)) < 0) {
         goto error;

diff --git a/src/storage/storage_backend_mpath.c b/src/storage/storage_backend_mpath.c
index 9a194842924c301fd834c85a00d94c4862a36f30..1e65a8d3cbbd7f2dc32fd090b0c762638791e100 100644 (file)
--- a/src/storage/storage_backend_mpath.c
+++ b/src/storage/storage_backend_mpath.c
@@ -1,7 +1,7 @@
 /*
  * storage_backend_mpath.c: storage backend for multipath handling
  *
- * Copyright (C) 2009-2011 Red Hat, Inc.
+ * Copyright (C) 2009-2011, 2013 Red Hat, Inc.
  * Copyright (C) 2009-2008 Dave Allan
  *
  * This library is free software; you can redistribute it and/or
@@ -46,13 +46,16 @@ virStorageBackendMpathUpdateVolTargetInfo(virStorageVolTargetPtr target,
 {
     int ret = -1;
     int fdret, fd = -1;
+    struct stat sb;
 
-    if ((fdret = virStorageBackendVolOpen(target->path)) < 0)
+    if ((fdret = virStorageBackendVolOpenCheckMode(target->path, &sb,
+                                                   VIR_STORAGE_VOL_OPEN_DEFAULT)) < 0)
         goto out;
     fd = fdret;
 
     if (virStorageBackendUpdateVolTargetInfoFD(target,
                                                fd,
+                                               &sb,
                                                allocation,
                                                capacity) < 0)
         goto out;

diff --git a/src/storage/storage_backend_scsi.c b/src/storage/storage_backend_scsi.c
index 57697997245207576e99468252016bab91488f06..14261217af0b38c78a662021076192a40e4fad82 100644 (file)
--- a/src/storage/storage_backend_scsi.c
+++ b/src/storage/storage_backend_scsi.c
@@ -1,7 +1,7 @@
 /*
  * storage_backend_scsi.c: storage backend for SCSI handling
  *
- * Copyright (C) 2007-2008 Red Hat, Inc.
+ * Copyright (C) 2007-2008, 2013 Red Hat, Inc.
  * Copyright (C) 2007-2008 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -138,13 +138,16 @@ virStorageBackendSCSIUpdateVolTargetInfo(virStorageVolTargetPtr target,
 {
     int fdret, fd = -1;
     int ret = -1;
+    struct stat sb;
 
-    if ((fdret = virStorageBackendVolOpen(target->path)) < 0)
+    if ((fdret = virStorageBackendVolOpenCheckMode(target->path, &sb,
+                                                   VIR_STORAGE_VOL_OPEN_DEFAULT)) < 0)
         goto cleanup;
     fd = fdret;
 
     if (virStorageBackendUpdateVolTargetInfoFD(target,
                                                fd,
+                                               &sb,
                                                allocation,
                                                capacity) < 0)
         goto cleanup;