From: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
Subject: [PATCH v2 3/3] hfsplus: implement attributes file creation functionality
This patch implements functionality of creation AttributesFile
metadata file on HFS+ volume in the case of absence of it.
It makes trying to open AttributesFile's B-tree during mount of
HFS+ volume. If HFS+ volume hasn't AttributesFile then a pointer
on AttributesFile's B-tree keeps as NULL. Thereby, when it is
discovered absence of AttributesFile on HFS+ volume in the begin
of xattr creation operation then AttributesFile will be created.
The creation of AttributesFile will have success in the case of
availability (2 * clump) free blocks on HFS+ volume. Otherwise,
creation operation is ended with error (-ENOSPC).
Signed-off-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
CC: Christoph Hellwig <hch@xxxxxxxxxxxxx>
CC: Hin-Tak Leung <htl10@xxxxxxxxxxxxxxxxxxxxx>
---
fs/hfsplus/hfsplus_fs.h | 9 +++
fs/hfsplus/super.c | 2 +
fs/hfsplus/xattr.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 151 insertions(+), 2 deletions(-)
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 1e36f18..08846425b 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -127,6 +127,14 @@ struct hfs_bnode {
#define HFS_BNODE_DELETED 4
/*
+ * Attributes file states
+ */
+#define HFSPLUS_EMPTY_ATTR_TREE 0
+#define HFSPLUS_CREATING_ATTR_TREE 1
+#define HFSPLUS_VALID_ATTR_TREE 2
+#define HFSPLUS_FAILED_ATTR_TREE 3
+
+/*
* HFS+ superblock info (built from Volume Header on disk)
*/
@@ -141,6 +149,7 @@ struct hfsplus_sb_info {
struct hfs_btree *ext_tree;
struct hfs_btree *cat_tree;
struct hfs_btree *attr_tree;
+ atomic_t attr_tree_state;
struct inode *alloc_file;
struct inode *hidden_dir;
struct nls_table *nls;
diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index 4c4d142..80875aa 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -474,12 +474,14 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
pr_err("failed to load catalog file\n");
goto out_close_ext_tree;
}
+ atomic_set(&sbi->attr_tree_state, HFSPLUS_EMPTY_ATTR_TREE);
if (vhdr->attr_file.total_blocks != 0) {
sbi->attr_tree = hfs_btree_open(sb, HFSPLUS_ATTR_CNID);
if (!sbi->attr_tree) {
pr_err("failed to load attributes file\n");
goto out_close_cat_tree;
}
+ atomic_set(&sbi->attr_tree_state, HFSPLUS_VALID_ATTR_TREE);
}
sb->s_xattr = hfsplus_xattr_handlers;
diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 568a45c..efc85b1 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -192,6 +192,143 @@ static void hfsplus_init_header_node(struct inode *attr_file,
*--rec_offsets = cpu_to_be16(offset);
}
+static int hfsplus_create_attributes_file(struct super_block *sb)
+{
+ int err = 0;
+ struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+ struct inode *attr_file;
+ struct hfsplus_inode_info *hip;
+ u32 clump_size;
+ u16 node_size = HFSPLUS_ATTR_TREE_NODE_SIZE;
+ char *buf;
+ int index, written;
+ struct address_space *mapping;
+ struct page *page;
+ int old_state = HFSPLUS_EMPTY_ATTR_TREE;
+
+ hfs_dbg(ATTR_MOD, "create_attr_file: ino %d\n", HFSPLUS_ATTR_CNID);
+
+check_attr_tree_state_again:
+ switch (atomic_read(&sbi->attr_tree_state)) {
+ case HFSPLUS_EMPTY_ATTR_TREE:
+ if (old_state != atomic_cmpxchg(&sbi->attr_tree_state,
+ old_state,
+ HFSPLUS_CREATING_ATTR_TREE))
+ goto check_attr_tree_state_again;
+ break;
+ case HFSPLUS_CREATING_ATTR_TREE:
+ /*
+ * This state means that another thread is in process
+ * of AttributesFile creation. Theoretically, it is
+ * possible to be here. But really __setxattr() method
+ * first of all calls hfs_find_init() for lookup in
+ * B-tree of CatalogFile. This method locks mutex of
+ * CatalogFile's B-tree. As a result, if some thread
+ * is inside AttributedFile creation operation then
+ * another threads will be waiting unlocking of
+ * CatalogFile's B-tree's mutex. However, if code will
+ * change then we will return error code (-EAGAIN) from
+ * here. Really, it means that first try to set of xattr
+ * fails with error but second attempt will have success.
+ */
+ return -EAGAIN;
+ case HFSPLUS_VALID_ATTR_TREE:
+ return 0;
+ case HFSPLUS_FAILED_ATTR_TREE:
+ return -EOPNOTSUPP;
+ default:
+ BUG();
+ }
+
+ attr_file = hfsplus_iget(sb, HFSPLUS_ATTR_CNID);
+ if (IS_ERR(attr_file)) {
+ pr_err("failed to load attributes file\n");
+ return PTR_ERR(attr_file);
+ }
+
+ BUG_ON(i_size_read(attr_file) != 0);
+
+ hip = HFSPLUS_I(attr_file);
+
+ clump_size = hfsplus_calc_btree_clump_size(sb->s_blocksize,
+ node_size,
+ sbi->sect_count,
+ HFSPLUS_ATTR_CNID);
+
+ mutex_lock(&hip->extents_lock);
+ hip->clump_blocks = clump_size >> sbi->alloc_blksz_shift;
+ mutex_unlock(&hip->extents_lock);
+
+ if (sbi->free_blocks <= (hip->clump_blocks << 1)) {
+ err = -ENOSPC;
+ goto end_attr_file_creation;
+ }
+
+ while (hip->alloc_blocks < hip->clump_blocks) {
+ err = hfsplus_file_extend(attr_file);
+ if (unlikely(err)) {
+ pr_err("failed to extend attributes file\n");
+ goto end_attr_file_creation;
+ }
+ hip->phys_size = attr_file->i_size =
+ (loff_t)hip->alloc_blocks << sbi->alloc_blksz_shift;
+ hip->fs_blocks = hip->alloc_blocks << sbi->fs_shift;
+ inode_set_bytes(attr_file, attr_file->i_size);
+ }
+
+ buf = kzalloc(node_size, GFP_NOFS);
+ if (!buf) {
+ pr_err("failed to allocate memory for header node\n");
+ err = -ENOMEM;
+ goto end_attr_file_creation;
+ }
+
+ hfsplus_init_header_node(attr_file, clump_size, buf, node_size);
+
+ mapping = attr_file->i_mapping;
+
+ index = 0;
+ written = 0;
+ for (; written < node_size; index++, written += PAGE_CACHE_SIZE) {
+ void *kaddr;
+
+ page = read_mapping_page(mapping, index, NULL);
+ if (IS_ERR(page)) {
+ err = PTR_ERR(page);
+ goto failed_header_node_init;
+ }
+
+ kaddr = kmap_atomic(page);
+ memcpy(kaddr, buf + written,
+ min_t(size_t, PAGE_CACHE_SIZE, node_size - written));
+ kunmap_atomic(kaddr);
+
+ set_page_dirty(page);
+ page_cache_release(page);
+ }
+
+ hfsplus_mark_inode_dirty(attr_file, HFSPLUS_I_ATTR_DIRTY);
+
+ sbi->attr_tree = hfs_btree_open(sb, HFSPLUS_ATTR_CNID);
+ if (!sbi->attr_tree)
+ pr_err("failed to load attributes file\n");
+
+failed_header_node_init:
+ kfree(buf);
+
+end_attr_file_creation:
+ iput(attr_file);
+
+ if (!err)
+ atomic_set(&sbi->attr_tree_state, HFSPLUS_VALID_ATTR_TREE);
+ else if (err == -ENOSPC)
+ atomic_set(&sbi->attr_tree_state, HFSPLUS_EMPTY_ATTR_TREE);
+ else
+ atomic_set(&sbi->attr_tree_state, HFSPLUS_FAILED_ATTR_TREE);
+
+ return err;
+}
+
int __hfsplus_setxattr(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
@@ -276,8 +413,9 @@ int __hfsplus_setxattr(struct inode *inode, const char *name,
}
if (!HFSPLUS_SB(inode->i_sb)->attr_tree) {
- err = -EOPNOTSUPP;
- goto end_setxattr;
+ err = hfsplus_create_attributes_file(inode->i_sb);
+ if (unlikely(err))
+ goto end_setxattr;
}
if (hfsplus_attr_exists(inode, name)) {
--
1.7.9.5
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