Merge tag 'v2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[mv-sheeva.git] / fs / udf / udf_i.h

diff --git a/fs/udf/udf_i.h b/fs/udf/udf_i.h
index e58d1de41073ccd8768d3cda0ba8c058b17dfa12..d1bd31ea724e8804e1467ff955bef46ad4aa0c5a 100644 (file)
--- a/fs/udf/udf_i.h
+++ b/fs/udf/udf_i.h
@@ -1,6 +1,18 @@
 #ifndef _UDF_I_H
 #define _UDF_I_H
 
+/*
+ * The i_data_sem and i_mutex serve for protection of allocation information
+ * of a regular files and symlinks. This includes all extents belonging to
+ * the file/symlink, a fact whether data are in-inode or in external data
+ * blocks, preallocation, goal block information... When extents are read,
+ * i_mutex or i_data_sem must be held (for reading is enough in case of
+ * i_data_sem). When extents are changed, i_data_sem must be held for writing
+ * and also i_mutex must be held.
+ *
+ * For directories i_mutex is used for all the necessary protection.
+ */
+
 struct udf_inode_info {
        struct timespec         i_crtime;
        /* Physical address of inode */
@@ -21,6 +33,7 @@ struct udf_inode_info {
                struct long_ad          *i_lad;
                __u8            *i_data;
        } i_ext;
+       struct rw_semaphore     i_data_sem;
        struct inode vfs_inode;
 };