ext4: xattr-in-inode support

Large xattr support is implemented for EXT4_FEATURE_INCOMPAT_EA_INODE.

If the size of an xattr value is larger than will fit in a single
external block, then the xattr value will be saved into the body
of an external xattr inode.

The also helps support a larger number of xattr, since only the headers
will be stored in the in-inode space or the single external block.

The inode is referenced from the xattr header via "e_value_inum",
which was formerly "e_value_block", but that field was never used.
The e_value_size still contains the xattr size so that listing
xattrs does not need to look up the inode if the data is not accessed.

struct ext4_xattr_entry {
        __u8    e_name_len;     /* length of name */
        __u8    e_name_index;   /* attribute name index */
        __le16  e_value_offs;   /* offset in disk block of value */
        __le32  e_value_inum;   /* inode in which value is stored */
        __le32  e_value_size;   /* size of attribute value */
        __le32  e_hash;         /* hash value of name and value */
        char    e_name[0];      /* attribute name */
};

The xattr inode is marked with the EXT4_EA_INODE_FL flag and also
holds a back-reference to the owning inode in its i_mtime field,
allowing the ext4/e2fsck to verify the correct inode is accessed.

[ Applied fix by Dan Carpenter to avoid freeing an ERR_PTR. ]

Lustre-Jira: https://jira.hpdd.intel.com/browse/LU-80
Lustre-bugzilla: https://bugzilla.lustre.org/show_bug.cgi?id=4424
Signed-off-by: Kalpak Shah <kalpak.shah@sun.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

fs/ext4/ext4.h

@@ -1797,6 +1797,7 @@ EXT4_FEATURE_INCOMPAT_FUNCS(encrypt,		ENCRYPT)
 					 EXT4_FEATURE_INCOMPAT_EXTENTS| \
 					 EXT4_FEATURE_INCOMPAT_64BIT| \
 					 EXT4_FEATURE_INCOMPAT_FLEX_BG| \
+					 EXT4_FEATURE_INCOMPAT_EA_INODE| \
 					 EXT4_FEATURE_INCOMPAT_MMP | \
 					 EXT4_FEATURE_INCOMPAT_INLINE_DATA | \
 					 EXT4_FEATURE_INCOMPAT_ENCRYPT | \
@@ -2230,6 +2231,12 @@ struct mmpd_data {
  */
 #define EXT4_MMP_MAX_CHECK_INTERVAL	300UL
 
+/*
+ * Maximum size of xattr attributes for FEATURE_INCOMPAT_EA_INODE 1Mb
+ * This limit is arbitrary, but is reasonable for the xattr API.
+ */
+#define EXT4_XATTR_MAX_LARGE_EA_SIZE    (1024 * 1024)
+
 /*
  * Function prototypes
  */
@@ -2242,6 +2249,10 @@ struct mmpd_data {
 # define ATTRIB_NORET	__attribute__((noreturn))
 # define NORET_AND	noreturn,
 
+struct ext4_xattr_ino_array {
+	unsigned int xia_count;		/* # of used item in the array */
+	unsigned int xia_inodes[0];
+};
 /* bitmap.c */
 extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);
 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
@@ -2489,6 +2500,7 @@ extern int ext4_truncate_restart_trans(handle_t *, struct inode *, int nblocks);
 extern void ext4_set_inode_flags(struct inode *);
 extern int ext4_alloc_da_blocks(struct inode *inode);
 extern void ext4_set_aops(struct inode *inode);
+extern int ext4_meta_trans_blocks(struct inode *, int nrblocks, int chunk);
 extern int ext4_writepage_trans_blocks(struct inode *);
 extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
 extern int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,

fs/ext4/ialloc.c

@@ -294,7 +294,6 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
 	 * as writing the quota to disk may need the lock as well.
 	 */
 	dquot_initialize(inode);
-	ext4_xattr_delete_inode(handle, inode);
 	dquot_free_inode(inode);
 	dquot_drop(inode);
 

fs/ext4/inline.c

@@ -61,7 +61,7 @@ static int get_max_inline_xattr_value_size(struct inode *inode,
 
 	/* Compute min_offs. */
 	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
-		if (!entry->e_value_block && entry->e_value_size) {
+		if (!entry->e_value_inum && entry->e_value_size) {
 			size_t offs = le16_to_cpu(entry->e_value_offs);
 			if (offs < min_offs)
 				min_offs = offs;

fs/ext4/inode.c

@@ -139,8 +139,6 @@ static void ext4_invalidatepage(struct page *page, unsigned int offset,
 				unsigned int length);
 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
-static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
-				  int pextents);
 
 /*
  * Test whether an inode is a fast symlink.
@@ -189,6 +187,8 @@ void ext4_evict_inode(struct inode *inode)
 {
 	handle_t *handle;
 	int err;
+	int extra_credits = 3;
+	struct ext4_xattr_ino_array *lea_ino_array = NULL;
 
 	trace_ext4_evict_inode(inode);
 
@@ -238,8 +238,8 @@ void ext4_evict_inode(struct inode *inode)
 	 * protection against it
 	 */
 	sb_start_intwrite(inode->i_sb);
-	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
-				    ext4_blocks_for_truncate(inode)+3);
+
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, extra_credits);
 	if (IS_ERR(handle)) {
 		ext4_std_error(inode->i_sb, PTR_ERR(handle));
 		/*
@@ -251,9 +251,36 @@ void ext4_evict_inode(struct inode *inode)
 		sb_end_intwrite(inode->i_sb);
 		goto no_delete;
 	}
-
 	if (IS_SYNC(inode))
 		ext4_handle_sync(handle);
+
+	/*
+	 * Delete xattr inode before deleting the main inode.
+	 */
+	err = ext4_xattr_delete_inode(handle, inode, &lea_ino_array);
+	if (err) {
+		ext4_warning(inode->i_sb,
+			     "couldn't delete inode's xattr (err %d)", err);
+		goto stop_handle;
+	}
+
+	if (!IS_NOQUOTA(inode))
+		extra_credits += 2 * EXT4_QUOTA_DEL_BLOCKS(inode->i_sb);
+
+	if (!ext4_handle_has_enough_credits(handle,
+			ext4_blocks_for_truncate(inode) + extra_credits)) {
+		err = ext4_journal_extend(handle,
+			ext4_blocks_for_truncate(inode) + extra_credits);
+		if (err > 0)
+			err = ext4_journal_restart(handle,
+			ext4_blocks_for_truncate(inode) + extra_credits);
+		if (err != 0) {
+			ext4_warning(inode->i_sb,
+				     "couldn't extend journal (err %d)", err);
+			goto stop_handle;
+		}
+	}
+
 	inode->i_size = 0;
 	err = ext4_mark_inode_dirty(handle, inode);
 	if (err) {
@@ -277,10 +304,10 @@ void ext4_evict_inode(struct inode *inode)
 	 * enough credits left in the handle to remove the inode from
 	 * the orphan list and set the dtime field.
 	 */
-	if (!ext4_handle_has_enough_credits(handle, 3)) {
-		err = ext4_journal_extend(handle, 3);
+	if (!ext4_handle_has_enough_credits(handle, extra_credits)) {
+		err = ext4_journal_extend(handle, extra_credits);
 		if (err > 0)
-			err = ext4_journal_restart(handle, 3);
+			err = ext4_journal_restart(handle, extra_credits);
 		if (err != 0) {
 			ext4_warning(inode->i_sb,
 				     "couldn't extend journal (err %d)", err);
@@ -315,8 +342,12 @@ void ext4_evict_inode(struct inode *inode)
 		ext4_clear_inode(inode);
 	else
 		ext4_free_inode(handle, inode);
+
 	ext4_journal_stop(handle);
 	sb_end_intwrite(inode->i_sb);
+
+	if (lea_ino_array != NULL)
+		ext4_xattr_inode_array_free(inode, lea_ino_array);
 	return;
 no_delete:
 	ext4_clear_inode(inode);	/* We must guarantee clearing of inode... */
@@ -5504,7 +5535,7 @@ static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
  *
  * Also account for superblock, inode, quota and xattr blocks
  */
-static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
+int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
 				  int pextents)
 {
 	ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);