e2fsprogs: Add stub functions for an xattr cache and struct to hold the header and block data.

Signed-off-by: Philip Tricca <flihp@twobit.us>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>

2 files changed, 176 insertions, 0 deletions

diff --git a/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch b/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch
new file mode 100644
index 0000000..f2e4582
--- /dev/null
+++ b/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch
@@ -0,0 +1,175 @@
+Add two new functions to manage a cache of xattr blocks as well as a new struct
+to build a linked list of xattr blocks.
+
+xattr_add_block: Adds a block to the cache. This function is supplied with a
+pointer to the head of a linked list of xattr blocks and an xattr block to add.
+The purpose of this cache is to allow sharing of what would otherwise be
+duplicate xattr blocks and so duplicates are not allowed in this cache. If an
+identical block is already in the cache a pointer to this block will be
+returned.
+
+xattr_rm_block: Removes a block from the cache. This function is supplied with
+a pointer to the cache and a node that shall be removed from the cache. The
+cache is searched for the node and the node is removed if found.
+
+Both functions are integrated into the 'set_inode_xattr'. Here the logic is
+rearranged to cope with associating preexisting xattr blocks with inodes as
+well as creating new blocks when necessary.
+
+Signed-off-by: Philip Tricca <flihp@twobit.us>
+
+Index: e2fsprogs-1.42.9/misc/xattr.c
+===================================================================
+--- e2fsprogs-1.42.9.orig/misc/xattr.c
++++ e2fsprogs-1.42.9/misc/xattr.c
+@@ -25,6 +25,19 @@
+ #define XATTR_STDERR(fmt, args...) do {} while (0)
+ #endif
+ 
++/* nodes for simple linked list to track xattr blocks, calling it a cache
++ * would be a stretch ...
++ */
++typedef struct xattr_node xattr_node_t;
++
++struct xattr_node {
++       struct ext2_ext_attr_header *header;
++       blk_t block;
++       struct xattr_node *next;
++};
++
++xattr_node_t *xattr_list_head = NULL;
++
+ /* structure for mapping xattr name prefix data */
+ typedef struct xattr_prefix {
+        int index;
+@@ -48,6 +61,17 @@ xattr_prefix_t xattr_prefixes [] = {
+        { 0 },
+ };
+ 
++/* free xattr node and the buffer holding the xattr block */
++static void
++xattr_free_node (xattr_node_t *node)
++{
++       if (node) {
++               if (node->header)
++                       free (node->header);
++               free (node);
++       }
++}
++
+ /* Free remaining resources after all files have been processed. */
+ void
+ xattr_cleanup ()
+@@ -260,6 +284,28 @@ out:
+        return ret;
+ }
+ 
++/* Add an xattr node to the list specified by head. This function will update
++ * head as necessary. It will return a pointer to the xattr_node_t added to the
++ * list. In the event that an identical xattr block is already on the list this
++ * function will return a pointer to the pre-existing node.
++ */
++static xattr_node_t*
++xattr_add_block (xattr_node_t **head, xattr_node_t *node)
++{
++       XATTR_STDERR ("Adding xattr to the the node list.\n");
++       return node;
++}
++
++/* Remove xattr node from list. Returns pointer to the node being removed.
++ * NOTE: We're not comparing the xattr blocks, just the nodes.
++ */
++static xattr_node_t*
++xattr_rm_block (xattr_node_t **head, xattr_node_t *node)
++{
++       XATTR_STDERR ("Removing xattr from the node list.\n");
++       return node;
++}
++
+ /* This is the entry point to the xattr module. This function copies the xattrs
+  * from the file at 'path' to the file system object at 'ino'.
+  *
+@@ -274,16 +320,21 @@ set_inode_xattr (ext2_filsys fs, ext2_in
+        errcode_t ret = 0;
+        char *buf = NULL;
+        struct ext2_inode inode = { 0 };
+-       blk_t block = 0;
+-       struct ext2_ext_attr_header *header = NULL;
++       xattr_node_t *node = NULL, *node_tmp = NULL;
+        uint32_t newcount = 0;
+ 
+        XATTR_STDERR ("Copying xattrs from %s to inode 0x%x.\n", path, ino);
++       /* Create an xattr_node_t for it and add it to the cache if appropriate */
++       if (!(node = calloc (1, sizeof (xattr_node_t)))) {
++               com_err (__func__, errno, "calloc");
++               ret = errno;
++               goto out;
++       }
+        /* Populate the xattr block for the file at path */
+-       if (ret = xattr_build_block (path, &header, fs->blocksize)) {
++       if (ret = xattr_build_block (path, &(node->header), fs->blocksize)) {
+                goto out;
+        }
+-       if (header == NULL) {
++       if (node->header == NULL) {
+                XATTR_STDERR ("set_inode_xattrs: no xattrs for %s\n", path);
+                goto out;
+        }
+@@ -291,23 +342,38 @@ set_inode_xattr (ext2_filsys fs, ext2_in
+                com_err(__func__, ret, "ext2fs_read_inode");
+                goto out;
+        }
+-       if (ret = ext2fs_alloc_block (fs, 0, NULL, &block)) {
+-               com_err(__func__, ret, "ext2fs_alloc_block: returned %d", ret);
++       if (!(node_tmp = xattr_add_block (&xattr_list_head, node))) {
++               fprintf (stderr, "Cannot add NULL node to xattr_block list.\n");
+                goto out;
+        }
+-       ext2fs_mark_block_bitmap2 (fs->block_map, block);
+-       XATTR_STDERR ("writing xattr block 0x%x to disk:\n", block);
+-       if (ret = ext2fs_write_ext_attr (fs, block, header)) {
+-               com_err(__func__, ret, "ext2fs_write_ext_attr: returned %d", ret);
+-               goto out;
++       if (node == node_tmp) {
++               /* xattr block is new: add to list & write to disk */
++               XATTR_STDERR ("no pre-existing xattr block, creating / adding\n");
++               if (ret = ext2fs_alloc_block (fs, 0, NULL, &node->block)) {
++                       com_err(__func__, ret, "ext2fs_alloc_block: returned %d", ret);
++                       xattr_rm_block (&xattr_list_head, node);
++                       goto out;
++               }
++               ext2fs_mark_block_bitmap2 (fs->block_map, node->block);
++               XATTR_STDERR ("writing xattr block 0x%x to disk:\n", node->block);
++               if (ret = ext2fs_write_ext_attr (fs, node->block, node->header)) {
++                       com_err(__func__, ret, "ext2fs_write_ext_attr: returned %d", ret);
++                       xattr_rm_block (&xattr_list_head, node);
++                       goto out;
++               }
++       } else {
++               /* already have an identical xattr block, free the one we just made */
++               XATTR_STDERR ("using xattr from existing block: 0x%x\n", node_tmp->block);
++               xattr_free_node (node);
++               node = node_tmp;
+        }
+        /* point inode for current file to xattr block, update block count and
+         * write inode to disk
+         */
+-       inode.i_file_acl = block;
++       inode.i_file_acl = node->block;
+        if (ret = ext2fs_adjust_ea_refcount2(fs,
+-                                       block,
+-                                       (char*)header,
++                                       node->block,
++                                       (char*)(node->header),
+                                        1,
+                                        &newcount))
+        {
+@@ -321,7 +387,6 @@ set_inode_xattr (ext2_filsys fs, ext2_in
+        if (ret = ext2fs_write_inode (fs, ino, &inode))
+                com_err(__func__, ret, "ext2fs_write_inode: returned %d", ret);
+ out:
+-       if (header)
+-               free (header);
++       xattr_free_node (node);
+        return ret;
+ }
diff --git a/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend b/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
index edc94d8..0705ec4 100644
--- a/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
+++ b/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
@@ -5,4 +5,5 @@ SRC_URI += " \
     file://mke2fs.c-create_inode.c-copy-xattrs.patch \
     file://lib-ext2fs-ext2_ext_attr.h-add-xattr-index.patch \
     file://misc-xattr-create-xattr-block.patch \
+    file://misc-xattr-create-xattr-block-node.patch \
 "