Changeset c2f4b6b in mainline for uspace/srv/vfs/vfs_ops.c

Timestamp:

2010-11-29T20:57:10Z (13 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

b38dfd8, cead2aa

Parents:

f07f6b2

Message:

Take the VFS node's content lock as reader even during writes when it
is safe to do so - i.e. the file system supports concurrent reads/writes
and the write never modifies the node size.

File:

• uspace/srv/vfs/vfs_ops.c (modified) (3 diffs)

uspace/srv/vfs/vfs_ops.c

@@ -781 +781 @@
 static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
 {
+        vfs_info_t *vi;
 
         /*
@@ -807 +808 @@
         fibril_mutex_lock(&file->lock);
 
+        vi = fs_handle_to_info(file->node->fs_handle);
+        assert(vi);
+
         /*
          * Lock the file's node so that no other client can read/write to it at
-         * the same time.
-         */
-        if (read)
+         * the same time unless the FS supports concurrent reads/writes and its
+         * write implementation does not modify the file size.
+         */
+        if (read || (vi->concurrent_read_write && vi->write_retains_size))
                 fibril_rwlock_read_lock(&file->node->contents_rwlock);
         else
@@ -857 +862 @@
         
         /* Unlock the VFS node. */
-        if (read)
+        if (read || (vi->concurrent_read_write && vi->write_retains_size))
                 fibril_rwlock_read_unlock(&file->node->contents_rwlock);
         else {