[Ocfs2-devel] [PATCH] ocfs2: Add directory block trailers.
Joel Becker
Joel.Becker at oracle.com
Wed Dec 10 18:25:12 PST 2008
From: Mark Fasheh <mfasheh at suse.com>
Future ocfs2 features metaecc and indexed directories need to store a
little bit of data in each dirblock. For compatibility, we place this
in a trailer at the end of the dirblock. The trailer plays itself as an
empty dirent, so that if the features are turned off, it can be reused
without requiring a tunefs scan.
This code adds the trailer and validates it when the block is read in.
[ Mark is the original author, but I reinserted this code before his
dir index work -- Joel ]
Signed-off-by: Joel Becker <joel.becker at oracle.com>
---
fs/ocfs2/dir.c | 163 ++++++++++++++++++++++++++++++++++++++++++++++-----
fs/ocfs2/ocfs2.h | 3 +
fs/ocfs2/ocfs2_fs.h | 25 ++++++++
3 files changed, 177 insertions(+), 14 deletions(-)
diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index 1ab2a3c..06077d0 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -84,6 +84,58 @@ static int ocfs2_do_extend_dir(struct super_block *sb,
struct buffer_head **new_bh);
/*
+ * These are distinct checks because future versions of the file system will
+ * want to have a trailing dirent structure independent of indexing.
+ */
+static int ocfs2_dir_has_trailer(struct inode *dir)
+{
+ return ocfs2_meta_ecc(OCFS2_SB(dir->i_sb));
+}
+
+static int ocfs2_supports_dir_trailer(struct ocfs2_super *osb)
+{
+ return ocfs2_meta_ecc(osb);
+}
+
+static inline unsigned int ocfs2_dir_trailer_blk_off(struct super_block *sb)
+{
+ return sb->s_blocksize - sizeof(struct ocfs2_dir_block_trailer);
+}
+
+#define ocfs2_trailer_from_bh(_bh, _sb) ((struct ocfs2_dir_block_trailer *) ((_bh)->b_data + ocfs2_dir_trailer_blk_off((_sb))))
+
+/*
+ * XXX: This is executed once on every dirent. We should consider optimizing
+ * it.
+ */
+static int ocfs2_skip_dir_trailer(struct inode *dir,
+ struct ocfs2_dir_entry *de,
+ unsigned long offset,
+ unsigned long blklen)
+{
+ unsigned long toff = blklen - sizeof(struct ocfs2_dir_block_trailer);
+
+ if (!ocfs2_dir_has_trailer(dir))
+ return 0;
+
+ if (offset != toff)
+ return 0;
+
+ return 1;
+}
+
+static void ocfs2_init_dir_trailer(struct super_block *sb,
+ struct buffer_head *bh)
+{
+ struct ocfs2_dir_block_trailer *trailer;
+
+ trailer = ocfs2_trailer_from_bh(bh, sb);
+ strcpy(trailer->db_signature, OCFS2_DIR_TRAILER_SIGNATURE);
+ trailer->db_compat_rec_len =
+ cpu_to_le16(sizeof(struct ocfs2_dir_block_trailer));
+}
+
+/*
* bh passed here can be an inode block or a dir data block, depending
* on the inode inline data flag.
*/
@@ -232,16 +284,39 @@ static int ocfs2_read_dir_block(struct inode *inode, u64 v_block,
{
int rc = 0;
struct buffer_head *tmp = *bh;
+ struct ocfs2_dir_block_trailer *trailer;
rc = ocfs2_read_virt_blocks(inode, v_block, 1, &tmp, flags,
ocfs2_validate_dir_block);
- if (rc)
+ if (rc) {
mlog_errno(rc);
+ goto out;
+ }
+
+ /*
+ * We check the trailer here rather than in
+ * ocfs2_validate_dir_block() because that function doesn't have
+ * the inode to test.
+ */
+ if (!(flags & OCFS2_BH_READAHEAD) &&
+ ocfs2_dir_has_trailer(inode)) {
+ trailer = ocfs2_trailer_from_bh(tmp, inode->i_sb);
+ if (!OCFS2_IS_VALID_DIR_TRAILER(trailer)) {
+ rc = -EIO;
+ ocfs2_error(inode->i_sb,
+ "Invalid dirblock #%llu: "
+ "signature = %.*s\n",
+ (unsigned long long)tmp->b_blocknr, 7,
+ trailer->db_signature);
+ goto out;
+ }
+ }
/* If ocfs2_read_virt_blocks() got us a new bh, pass it up. */
- if (!rc && !*bh)
+ if (!*bh)
*bh = tmp;
+out:
return rc ? -EIO : 0;
}
@@ -573,6 +648,9 @@ int __ocfs2_add_entry(handle_t *handle,
goto bail;
}
+ if (ocfs2_skip_dir_trailer(dir, de, offset, size))
+ goto next;
+
if (ocfs2_dirent_would_fit(de, rec_len)) {
dir->i_mtime = dir->i_ctime = CURRENT_TIME;
retval = ocfs2_mark_inode_dirty(handle, dir, parent_fe_bh);
@@ -614,6 +692,7 @@ int __ocfs2_add_entry(handle_t *handle,
retval = 0;
goto bail;
}
+next:
offset += le16_to_cpu(de->rec_len);
de = (struct ocfs2_dir_entry *) ((char *) de + le16_to_cpu(de->rec_len));
}
@@ -1051,9 +1130,15 @@ int ocfs2_empty_dir(struct inode *inode)
return !priv.seen_other;
}
-static void ocfs2_fill_initial_dirents(struct inode *inode,
- struct inode *parent,
- char *start, unsigned int size)
+/*
+ * Fills "." and ".." dirents in a new directory block. Returns dirent for
+ * "..", which might be used during creation of a directory with a trailing
+ * header. It is otherwise safe to ignore the return code.
+ */
+static struct ocfs2_dir_entry *ocfs2_fill_initial_dirents(struct inode *inode,
+ struct inode *parent,
+ char *start,
+ unsigned int size)
{
struct ocfs2_dir_entry *de = (struct ocfs2_dir_entry *)start;
@@ -1070,6 +1155,8 @@ static void ocfs2_fill_initial_dirents(struct inode *inode,
de->name_len = 2;
strcpy(de->name, "..");
ocfs2_set_de_type(de, S_IFDIR);
+
+ return de;
}
/*
@@ -1122,10 +1209,15 @@ static int ocfs2_fill_new_dir_el(struct ocfs2_super *osb,
struct ocfs2_alloc_context *data_ac)
{
int status;
+ unsigned int size = osb->sb->s_blocksize;
struct buffer_head *new_bh = NULL;
+ struct ocfs2_dir_entry *de;
mlog_entry_void();
+ if (ocfs2_supports_dir_trailer(osb))
+ size = ocfs2_dir_trailer_blk_off(parent->i_sb);
+
status = ocfs2_do_extend_dir(osb->sb, handle, inode, fe_bh,
data_ac, NULL, &new_bh);
if (status < 0) {
@@ -1143,8 +1235,9 @@ static int ocfs2_fill_new_dir_el(struct ocfs2_super *osb,
}
memset(new_bh->b_data, 0, osb->sb->s_blocksize);
- ocfs2_fill_initial_dirents(inode, parent, new_bh->b_data,
- osb->sb->s_blocksize);
+ de = ocfs2_fill_initial_dirents(inode, parent, new_bh->b_data, size);
+ if (ocfs2_supports_dir_trailer(osb))
+ ocfs2_init_dir_trailer(parent->i_sb, new_bh);
status = ocfs2_journal_dirty(handle, new_bh);
if (status < 0) {
@@ -1185,13 +1278,27 @@ int ocfs2_fill_new_dir(struct ocfs2_super *osb,
data_ac);
}
+/*
+ * Expand rec_len of the rightmost dirent in a directory block so that it
+ * contains the end of our valid space for dirents. We do this during
+ * expansion from an inline directory to one with extents. The first dir block
+ * in that case is taken from the inline data portion of the inode block.
+ *
+ * We add the dir trailer if this filesystem wants it.
+ */
static void ocfs2_expand_last_dirent(char *start, unsigned int old_size,
- unsigned int new_size)
+ struct super_block *sb)
{
struct ocfs2_dir_entry *de;
struct ocfs2_dir_entry *prev_de;
char *de_buf, *limit;
- unsigned int bytes = new_size - old_size;
+ unsigned int new_size = sb->s_blocksize;
+ unsigned int bytes;
+
+ if (ocfs2_supports_dir_trailer(OCFS2_SB(sb)))
+ new_size = ocfs2_dir_trailer_blk_off(sb);
+
+ bytes = new_size - old_size;
limit = start + old_size;
de_buf = start;
@@ -1308,8 +1415,9 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
memcpy(dirdata_bh->b_data, di->id2.i_data.id_data, i_size_read(dir));
memset(dirdata_bh->b_data + i_size_read(dir), 0,
sb->s_blocksize - i_size_read(dir));
- ocfs2_expand_last_dirent(dirdata_bh->b_data, i_size_read(dir),
- sb->s_blocksize);
+ ocfs2_expand_last_dirent(dirdata_bh->b_data, i_size_read(dir), sb);
+ if (ocfs2_supports_dir_trailer(osb))
+ ocfs2_init_dir_trailer(sb, dirdata_bh);
ret = ocfs2_journal_dirty(handle, dirdata_bh);
if (ret) {
@@ -1596,9 +1704,15 @@ do_extend:
goto bail;
}
memset(new_bh->b_data, 0, sb->s_blocksize);
+
de = (struct ocfs2_dir_entry *) new_bh->b_data;
de->inode = 0;
- de->rec_len = cpu_to_le16(sb->s_blocksize);
+ if (ocfs2_dir_has_trailer(dir)) {
+ de->rec_len = cpu_to_le16(ocfs2_dir_trailer_blk_off(sb));
+ ocfs2_init_dir_trailer(sb, new_bh);
+ } else {
+ de->rec_len = cpu_to_le16(sb->s_blocksize);
+ }
status = ocfs2_journal_dirty(handle, new_bh);
if (status < 0) {
mlog_errno(status);
@@ -1640,11 +1754,21 @@ static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
unsigned int *blocks_wanted)
{
int ret;
+ struct super_block *sb = dir->i_sb;
struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
struct ocfs2_dir_entry *de, *last_de = NULL;
char *de_buf, *limit;
unsigned long offset = 0;
- unsigned int rec_len, new_rec_len;
+ unsigned int rec_len, new_rec_len, free_space = dir->i_sb->s_blocksize;
+
+ /*
+ * This calculates how many free bytes we'd have in block zero, should
+ * this function force expansion to an extent tree.
+ */
+ if (ocfs2_supports_dir_trailer(OCFS2_SB(sb)))
+ free_space = ocfs2_dir_trailer_blk_off(sb) - i_size_read(dir);
+ else
+ free_space = dir->i_sb->s_blocksize - i_size_read(dir);
de_buf = di->id2.i_data.id_data;
limit = de_buf + i_size_read(dir);
@@ -1661,6 +1785,11 @@ static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
ret = -EEXIST;
goto out;
}
+ /*
+ * No need to check for a trailing dirent record here as
+ * they're not used for inline dirs.
+ */
+
if (ocfs2_dirent_would_fit(de, rec_len)) {
/* Ok, we found a spot. Return this bh and let
* the caller actually fill it in. */
@@ -1681,7 +1810,7 @@ static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
* dirent can be found.
*/
*blocks_wanted = 1;
- new_rec_len = le16_to_cpu(last_de->rec_len) + (dir->i_sb->s_blocksize - i_size_read(dir));
+ new_rec_len = le16_to_cpu(last_de->rec_len) + free_space;
if (new_rec_len < (rec_len + OCFS2_DIR_REC_LEN(last_de->name_len)))
*blocks_wanted = 2;
@@ -1740,6 +1869,11 @@ static int ocfs2_find_dir_space_el(struct inode *dir, const char *name,
status = -EEXIST;
goto bail;
}
+
+ if (ocfs2_skip_dir_trailer(dir, de, offset,
+ dir->i_sb->s_blocksize))
+ goto next;
+
if (ocfs2_dirent_would_fit(de, rec_len)) {
/* Ok, we found a spot. Return this bh and let
* the caller actually fill it in. */
@@ -1748,6 +1882,7 @@ static int ocfs2_find_dir_space_el(struct inode *dir, const char *name,
status = 0;
goto bail;
}
+next:
offset += le16_to_cpu(de->rec_len);
de = (struct ocfs2_dir_entry *)((char *) de + le16_to_cpu(de->rec_len));
}
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index bad87d0..ad5c24a 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -470,6 +470,9 @@ static inline int ocfs2_uses_extended_slot_map(struct ocfs2_super *osb)
#define OCFS2_IS_VALID_XATTR_BLOCK(ptr) \
(!strcmp((ptr)->xb_signature, OCFS2_XATTR_BLOCK_SIGNATURE))
+#define OCFS2_IS_VALID_DIR_TRAILER(ptr) \
+ (!strcmp((ptr)->db_signature, OCFS2_DIR_TRAILER_SIGNATURE))
+
static inline unsigned long ino_from_blkno(struct super_block *sb,
u64 blkno)
{
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 4e20f50..e6e7cb0 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -65,6 +65,7 @@
#define OCFS2_EXTENT_BLOCK_SIGNATURE "EXBLK01"
#define OCFS2_GROUP_DESC_SIGNATURE "GROUP01"
#define OCFS2_XATTR_BLOCK_SIGNATURE "XATTR01"
+#define OCFS2_DIR_TRAILER_SIGNATURE "DIRTRL1"
/* Compatibility flags */
#define OCFS2_HAS_COMPAT_FEATURE(sb,mask) \
@@ -746,6 +747,30 @@ struct ocfs2_dir_entry {
} __attribute__ ((packed));
/*
+ * Per-block record for the unindexed directory btree. This is carefully
+ * crafted so that the rec_len and name_len records of an ocfs2_dir_entry are
+ * mirrored. That way, the directory manipulation code needs a minimal amount
+ * of update.
+ *
+ * NOTE: Keep this structure aligned to a multiple of 4 bytes.
+ */
+struct ocfs2_dir_block_trailer {
+/*00*/ __le64 db_compat_inode; /* Always zero. Was inode */
+
+ __le16 db_compat_rec_len; /* Backwards compatible with
+ * ocfs2_dir_entry. */
+ __u8 db_compat_name_len; /* Always zero. Was name_len */
+ __u8 db_reserved0;
+ __le16 db_reserved1;
+ __le16 db_free_rec_len; /* Size of largest empty hole
+ * in this block. (unused) */
+ __u8 db_signature[8]; /* Signature for verification */
+ __le64 db_reserved2;
+ __le64 db_free_next; /* Next block in list (unused) */
+ __le64 db_check; /* Error checking */
+};
+
+/*
* On disk allocator group structure for OCFS2
*/
struct ocfs2_group_desc
--
1.5.6.5
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