Illumos #3742

3742 zfs comments need cleaner, more consistent style
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3742
  illumos/illumos-gate@f717074149

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. The change to zfs_vfsops.c was dropped because it involves
   zfs_mount_label_policy, which does not exist in the Linux port.

include/sys/ddt.h

@@ -63,16 +63,15 @@ enum ddt_class {
  */
 typedef struct ddt_key {
 	zio_cksum_t	ddk_cksum;	/* 256-bit block checksum */
-	uint64_t	ddk_prop;	/* LSIZE, PSIZE, compression */
+	/*
+	 * Encoded with logical & physical size, and compression, as follows:
+	 *   +-------+-------+-------+-------+-------+-------+-------+-------+
+	 *   |   0   |   0   |   0   | comp  |     PSIZE     |     LSIZE     |
+	 *   +-------+-------+-------+-------+-------+-------+-------+-------+
+	 */
+	uint64_t	ddk_prop;
 } ddt_key_t;
 
-/*
- * ddk_prop layout:
- *
- *	+-------+-------+-------+-------+-------+-------+-------+-------+
- *	|   0	|   0	|   0	| comp	|     PSIZE	|     LSIZE	|
- *	+-------+-------+-------+-------+-------+-------+-------+-------+
- */
 #define	DDK_GET_LSIZE(ddk)	\
 	BF64_GET_SB((ddk)->ddk_prop, 0, 16, SPA_MINBLOCKSHIFT, 1)
 #define	DDK_SET_LSIZE(ddk, x)	\

include/sys/dnode.h

@@ -145,9 +145,8 @@ typedef struct dnode_phys {
 
 typedef struct dnode {
 	/*
-	 * dn_struct_rwlock protects the structure of the dnode,
+	 * Protects the structure of the dnode, including the number of levels
-	 * including the number of levels of indirection (dn_nlevels),
+	 * of indirection (dn_nlevels), dn_maxblkid, and dn_next_*
-	 * dn_maxblkid, and dn_next_*
 	 */
 	krwlock_t dn_struct_rwlock;
 

include/sys/dsl_pool.h

@@ -112,6 +112,7 @@ typedef struct dsl_pool {
 
 	/*
 	 * Protects administrative changes (properties, namespace)
+	 *
 	 * It is only held for write in syncing context.  Therefore
 	 * syncing context does not need to ever have it for read, since
 	 * nobody else could possibly have it for write.

include/sys/sa_impl.h

@@ -150,6 +150,7 @@ struct sa_os {
 
 /*
  * header for all bonus and spill buffers.
+ *
  * The header has a fixed portion with a variable number
  * of "lengths" depending on the number of variable sized
  * attribues which are determined by the "layout number"
@@ -158,29 +159,27 @@ struct sa_os {
 #define	SA_MAGIC	0x2F505A  /* ZFS SA */
 typedef struct sa_hdr_phys {
 	uint32_t sa_magic;
-	uint16_t sa_layout_info;  /* Encoded with hdrsize and layout number */
+	/*
+	 * Encoded with hdrsize and layout number as follows:
+	 * 16      10       0
+	 * +--------+-------+
+	 * | hdrsz  |layout |
+	 * +--------+-------+
+	 *
+	 * Bits 0-10 are the layout number
+	 * Bits 11-16 are the size of the header.
+	 * The hdrsize is the number * 8
+	 *
+	 * For example.
+	 * hdrsz of 1 ==> 8 byte header
+	 *          2 ==> 16 byte header
+	 *
+	 */
+	uint16_t sa_layout_info;
 	uint16_t sa_lengths[1];	/* optional sizes for variable length attrs */
 	/* ... Data follows the lengths.  */
 } sa_hdr_phys_t;
 
-/*
- * sa_hdr_phys -> sa_layout_info
- *
- * 16      10       0
- * +--------+-------+
- * | hdrsz  |layout |
- * +--------+-------+
- *
- * Bits 0-10 are the layout number
- * Bits 11-16 are the size of the header.
- * The hdrsize is the number * 8
- *
- * For example.
- * hdrsz of 1 ==> 8 byte header
- *          2 ==> 16 byte header
- *
- */
-
 #define	SA_HDR_LAYOUT_NUM(hdr) BF32_GET(hdr->sa_layout_info, 0, 10)
 #define	SA_HDR_SIZE(hdr) BF32_GET_SB(hdr->sa_layout_info, 10, 6, 3, 0)
 #define	SA_HDR_LAYOUT_INFO_ENCODE(x, num, size) \

include/sys/spa_impl.h

@@ -239,7 +239,7 @@ struct spa {
 	spa_stats_t	spa_stats;		/* assorted spa statistics */
 
 	/*
-	 * spa_refcnt & spa_config_lock must be the last elements
+	 * spa_refcount & spa_config_lock must be the last elements
 	 * because refcount_t changes size based on compilation options.
 	 * In order for the MDB module to function correctly, the other
 	 * fields must remain in the same location.

include/sys/space_map.h

@@ -94,7 +94,6 @@ struct space_map_ops {
  *   63  62    60 59        50 49                               0
  *
  *
- *
  * non-debug entry
  *
  *    1               47                   1           15

include/sys/unique.h

@@ -26,8 +26,6 @@
 #ifndef	_SYS_UNIQUE_H
 #define	_SYS_UNIQUE_H
 
-
-
 #include <sys/zfs_context.h>
 
 #ifdef	__cplusplus
@@ -42,7 +40,7 @@ void unique_fini(void);
 
 /*
  * Return a new unique value (which will not be uniquified against until
- * it is unique_insert()-ed.
+ * it is unique_insert()-ed).
  */
 uint64_t unique_create(void);
 

include/sys/vdev_impl.h

@@ -254,12 +254,13 @@ typedef struct vdev_label {
 #define	VDD_METASLAB	0x01
 #define	VDD_DTL		0x02
 
+/* Offset of embedded boot loader region on each label */
+#define	VDEV_BOOT_OFFSET	(2 * sizeof (vdev_label_t))
 /*
- * Size and offset of embedded boot loader region on each label.
+ * Size of embedded boot loader region on each label.
  * The total size of the first two labels plus the boot area is 4MB.
  */
-#define	VDEV_BOOT_OFFSET	(2 * sizeof (vdev_label_t))
+#define	VDEV_BOOT_SIZE		(7ULL << 19)			/* 3.5M */
-#define	VDEV_BOOT_SIZE		(7ULL << 19)			/* 3.5M	*/
 
 /*
  * Size of label regions at the start and end of each leaf device.
@@ -326,8 +327,9 @@ extern uint64_t vdev_get_min_asize(vdev_t *vd);
 extern void vdev_set_min_asize(vdev_t *vd);
 
 /*
- * zdb uses this tunable, so it must be declared here to make lint happy.
+ * Global variables
  */
+/* zdb uses this tunable, so it must be declared here to make lint happy. */
 extern int zfs_vdev_cache_size;
 
 #ifdef	__cplusplus

include/sys/zap.h

@@ -86,18 +86,22 @@ extern "C" {
 #endif
 
 /*
- * The matchtype specifies which entry will be accessed.
+ * Specifies matching criteria for ZAP lookups.
- * MT_EXACT: only find an exact match (non-normalized)
- * MT_FIRST: find the "first" normalized (case and Unicode
- *     form) match; the designated "first" match will not change as long
- *     as the set of entries with this normalization doesn't change
- * MT_BEST: if there is an exact match, find that, otherwise find the
- *     first normalized match
  */
 typedef enum matchtype
 {
+	/* Only find an exact match (non-normalized) */
 	MT_EXACT,
+	/*
+	 * If there is an exact match, find that, otherwise find the
+	 * first normalized match.
+	 */
 	MT_BEST,
+	/*
+	 * Find the "first" normalized (case and Unicode form) match;
+	 * the designated "first" match will not change as long as the
+	 * set of entries with this normalization doesn't change.
+	 */
 	MT_FIRST
 } matchtype_t;
 
@@ -174,16 +178,21 @@ int zap_destroy(objset_t *ds, uint64_t zapobj, dmu_tx_t *tx);
  * call will fail and return EINVAL.
  *
  * If 'integer_size' is equal to or larger than the attribute's integer
- * size, the call will succeed and return 0.  * When converting to a
+ * size, the call will succeed and return 0.
- * larger integer size, the integers will be treated as unsigned (ie. no
+ *
- * sign-extension will be performed).
+ * When converting to a larger integer size, the integers will be treated as
+ * unsigned (ie. no sign-extension will be performed).
  *
  * 'num_integers' is the length (in integers) of 'buf'.
  *
  * If the attribute is longer than the buffer, as many integers as will
  * fit will be transferred to 'buf'.  If the entire attribute was not
  * transferred, the call will return EOVERFLOW.
- *
+ */
+int zap_lookup(objset_t *ds, uint64_t zapobj, const char *name,
+    uint64_t integer_size, uint64_t num_integers, void *buf);
+
+/*
  * If rn_len is nonzero, realname will be set to the name of the found
  * entry (which may be different from the requested name if matchtype is
  * not MT_EXACT).
@@ -191,8 +200,6 @@ int zap_destroy(objset_t *ds, uint64_t zapobj, dmu_tx_t *tx);
  * If normalization_conflictp is not NULL, it will be set if there is
  * another name with the same case/unicode normalized form.
  */
-int zap_lookup(objset_t *ds, uint64_t zapobj, const char *name,
-    uint64_t integer_size, uint64_t num_integers, void *buf);
 int zap_lookup_norm(objset_t *ds, uint64_t zapobj, const char *name,
     uint64_t integer_size, uint64_t num_integers, void *buf,
     matchtype_t mt, char *realname, int rn_len,

include/sys/zap_leaf.h

@@ -101,6 +101,7 @@ typedef enum zap_chunk_type {
  */
 typedef struct zap_leaf_phys {
 	struct zap_leaf_header {
+		/* Public to ZAP */
 		uint64_t lh_block_type;		/* ZBT_LEAF */
 		uint64_t lh_pad1;
 		uint64_t lh_prefix;		/* hash prefix of this leaf */
@@ -109,8 +110,7 @@ typedef struct zap_leaf_phys {
 		uint16_t lh_nentries;		/* number of entries */
 		uint16_t lh_prefix_len;		/* num bits used to id this */
 
-/* above is accessable to zap, below is zap_leaf private */
+		/* Private to zap_leaf */
-
 		uint16_t lh_freelist;		/* chunk head of free list */
 		uint8_t lh_flags;		/* ZLF_* flags */
 		uint8_t lh_pad2[11];
@@ -161,13 +161,13 @@ typedef struct zap_leaf {
 
 
 typedef struct zap_entry_handle {
-	/* below is set by zap_leaf.c and is public to zap.c */
+	/* Set by zap_leaf and public to ZAP */
 	uint64_t zeh_num_integers;
 	uint64_t zeh_hash;
 	uint32_t zeh_cd;
 	uint8_t zeh_integer_size;
 
-	/* below is private to zap_leaf.c */
+	/* Private to zap_leaf */
 	uint16_t zeh_fakechunk;
 	uint16_t *zeh_chunkp;
 	zap_leaf_t *zeh_leaf;
@@ -202,7 +202,7 @@ extern int zap_entry_read_name(struct zap *zap, const zap_entry_handle_t *zeh,
 /*
  * Replace the value of an existing entry.
  *
- * zap_entry_update may fail if it runs out of space (ENOSPC).
+ * May fail if it runs out of space (ENOSPC).
  */
 extern int zap_entry_update(zap_entry_handle_t *zeh,
     uint8_t integer_size, uint64_t num_integers, const void *buf);
@@ -221,10 +221,7 @@ extern int zap_entry_create(zap_leaf_t *l, struct zap_name *zn, uint32_t cd,
     uint8_t integer_size, uint64_t num_integers, const void *buf,
     zap_entry_handle_t *zeh);
 
-/*
+/* Determine whether there is another entry with the same normalized form. */
- * Return true if there are additional entries with the same normalized
- * form.
- */
 extern boolean_t zap_entry_normalization_conflict(zap_entry_handle_t *zeh,
     struct zap_name *zn, const char *name, struct zap *zap);
 

include/sys/zfs_acl.h

@@ -47,7 +47,8 @@ struct znode_phys;
 #define	ZFS_ACL_VERSION		ZFS_ACL_VERSION_FUID
 
 /*
- * ZFS ACLs are store in various forms.
+ * ZFS ACLs (Access Control Lists) are stored in various forms.
+ *
  * Files created with ACL version ZFS_ACL_VERSION_INITIAL
  * will all be created with fixed length ACEs of type
  * zfs_oldace_t.
@@ -137,8 +138,8 @@ typedef struct acl_ops {
 	size_t		(*ace_size)(void *acep); /* how big is this ace */
 	size_t		(*ace_abstract_size)(void); /* sizeof abstract entry */
 	int		(*ace_mask_off)(void); /* off of access mask in ace */
+	/* ptr to data if any */
 	int		(*ace_data)(void *acep, void **datap);
-			    /* ptr to data if any */
 } acl_ops_t;
 
 /*

include/sys/zfs_rlock.h

@@ -26,8 +26,6 @@
 #ifndef	_SYS_FS_ZFS_RLOCK_H
 #define	_SYS_FS_ZFS_RLOCK_H
 
-
-
 #ifdef	__cplusplus
 extern "C" {
 #endif
@@ -58,16 +56,14 @@ typedef struct rl {
 } rl_t;
 
 /*
- * Lock a range (offset, length) as either shared (READER)
+ * Lock a range (offset, length) as either shared (RL_READER)
- * or exclusive (WRITER or APPEND). APPEND is a special type that
+ * or exclusive (RL_WRITER or RL_APPEND).  RL_APPEND is a special type that
- * is converted to WRITER that specified to lock from the start of the
+ * is converted to RL_WRITER that specified to lock from the start of the
- * end of file.  zfs_range_lock() returns the range lock structure.
+ * end of file.  Returns the range lock structure.
  */
 rl_t *zfs_range_lock(znode_t *zp, uint64_t off, uint64_t len, rl_type_t type);
 
-/*
+/* Unlock range and destroy range lock structure. */
- * Unlock range and destroy range lock structure.
- */
 void zfs_range_unlock(rl_t *rl);
 
 /*
@@ -77,7 +73,8 @@ void zfs_range_unlock(rl_t *rl);
 void zfs_range_reduce(rl_t *rl, uint64_t off, uint64_t len);
 
 /*
- * AVL comparison function used to compare range locks
+ * AVL comparison function used to order range locks
+ * Locks are ordered on the start offset of the range.
  */
 int zfs_range_compare(const void *arg1, const void *arg2);
 

include/sys/zfs_znode.h

@@ -139,8 +139,9 @@ extern "C" {
 
 #define	ZFS_MAX_BLOCKSIZE	(SPA_MAXBLOCKSIZE)
 
-/* Path component length */
 /*
+ * Path component length
+ *
  * The generic fs code uses MAXNAMELEN to represent
  * what the largest component length is.  Unfortunately,
  * this length includes the terminating NULL.  ZFS needs
@@ -248,11 +249,7 @@ typedef struct znode {
 
 #define	S_ISDEV(mode)	(S_ISCHR(mode) || S_ISBLK(mode) || S_ISFIFO(mode))
 
-/*
+/* Called on entry to each ZFS vnode and vfs operation  */
- * ZFS_ENTER() is called on entry to each ZFS inode and vfs operation.
- * ZFS_EXIT() must be called before exitting the vop.
- * ZFS_VERIFY_ZP() verifies the znode is valid.
- */
 #define	ZFS_ENTER(zsb) \
 	{ \
 		rrw_enter_read(&(zsb)->z_teardown_lock, FTAG); \
@@ -262,12 +259,14 @@ typedef struct znode {
 		} \
 	}
 
+/* Must be called before exiting the vop */
 #define	ZFS_EXIT(zsb) \
 	{ \
 		rrw_exit(&(zsb)->z_teardown_lock, FTAG); \
 		tsd_exit(); \
 	}
 
+/* Verifies the znode is valid */
 #define	ZFS_VERIFY_ZP(zp) \
 	if ((zp)->z_sa_hdl == NULL) { \
 		ZFS_EXIT(ZTOZSB(zp)); \
@@ -289,15 +288,14 @@ typedef struct znode {
 #define	ZFS_OBJ_HOLD_OWNED(zsb, obj_num) \
 	mutex_owned(ZFS_OBJ_MUTEX((zsb), (obj_num)))
 
-/*
+/* Encode ZFS stored time values from a struct timespec */
- * Macros to encode/decode ZFS stored time values from/to struct timespec
- */
 #define	ZFS_TIME_ENCODE(tp, stmp)		\
 {						\
 	(stmp)[0] = (uint64_t)(tp)->tv_sec;	\
 	(stmp)[1] = (uint64_t)(tp)->tv_nsec;	\
 }
 
+/* Decode ZFS stored time values to a struct timespec */
 #define	ZFS_TIME_DECODE(tp, stmp)		\
 {						\
 	(tp)->tv_sec = (time_t)(stmp)[0];		\

include/sys/zil.h

@@ -242,6 +242,12 @@ typedef struct {
  * information needed for replaying the create.  If the
  * file doesn't have any actual ACEs then the lr_aclcnt
  * would be zero.
+ *
+ * After lr_acl_flags, there are a lr_acl_bytes number of variable sized ace's.
+ * If create is also setting xvattr's, then acl data follows xvattr.
+ * If ACE FUIDs are needed then they will follow the xvattr_t.  Following
+ * the FUIDs will be the domain table information.  The FUIDs for the owner
+ * and group will be in lr_create.  Name follows ACL data.
  */
 typedef struct {
 	lr_create_t	lr_create;	/* common create portion */
@@ -250,13 +256,6 @@ typedef struct {
 	uint64_t	lr_fuidcnt;	/* number of real fuids */
 	uint64_t	lr_acl_bytes;	/* number of bytes in ACL */
 	uint64_t	lr_acl_flags;	/* ACL flags */
-	/* lr_acl_bytes number of variable sized ace's follows */
-	/* if create is also setting xvattr's, then acl data follows xvattr */
-	/* if ACE FUIDs are needed then they will follow the xvattr_t */
-	/* Following the FUIDs will be the domain table information. */
-	/* The FUIDs for the owner and group will be in the lr_create */
-	/* portion of the record. */
-	/* name follows ACL data */
 } lr_acl_create_t;
 
 typedef struct {

include/sys/zio_compress.h

@@ -33,11 +33,10 @@
 extern "C" {
 #endif
 
-/*
+/* Common signature for all zio compress functions. */
- * Common signature for all zio compress/decompress functions.
- */
 typedef size_t zio_compress_func_t(void *src, void *dst,
     size_t s_len, size_t d_len, int);
+/* Common signature for all zio decompress functions. */
 typedef int zio_decompress_func_t(void *src, void *dst,
     size_t s_len, size_t d_len, int);
 

module/zfs/arc.c

@@ -58,11 +58,11 @@
  * tight.
  *
  * 3. The Megiddo and Modha model assumes a fixed page size. All
- * elements of the cache are therefor exactly the same size.  So
+ * elements of the cache are therefore exactly the same size.  So
  * when adjusting the cache size following a cache miss, its simply
  * a matter of choosing a single page to evict.  In our model, we
  * have variable sized cache blocks (rangeing from 512 bytes to
- * 128K bytes).  We therefor choose a set of blocks to evict to make
+ * 128K bytes).  We therefore choose a set of blocks to evict to make
  * space for a cache miss that approximates as closely as possible
  * the space used by the new block.
  *
@@ -77,7 +77,7 @@
  * ways: 1) via a hash table lookup using the DVA as a key,
  * or 2) via one of the ARC lists.  The arc_read() interface
  * uses method 1, while the internal arc algorithms for
- * adjusting the cache use method 2.  We therefor provide two
+ * adjusting the cache use method 2.  We therefore provide two
  * types of locks: 1) the hash table lock array, and 2) the
  * arc list locks.
  *
@@ -431,7 +431,7 @@ static arc_stats_t arc_stats = {
 #define	ARCSTAT(stat)	(arc_stats.stat.value.ui64)
 
 #define	ARCSTAT_INCR(stat, val) \
-	atomic_add_64(&arc_stats.stat.value.ui64, (val));
+	atomic_add_64(&arc_stats.stat.value.ui64, (val))
 
 #define	ARCSTAT_BUMP(stat)	ARCSTAT_INCR(stat, 1)
 #define	ARCSTAT_BUMPDOWN(stat)	ARCSTAT_INCR(stat, -1)
@@ -665,9 +665,7 @@ uint64_t zfs_crc64_table[256];
 #define	l2arc_writes_sent	ARCSTAT(arcstat_l2_writes_sent)
 #define	l2arc_writes_done	ARCSTAT(arcstat_l2_writes_done)
 
-/*
+/* L2ARC Performance Tunables */
- * L2ARC Performance Tunables
- */
 unsigned long l2arc_write_max = L2ARC_WRITE_SIZE;	/* def max write size */
 unsigned long l2arc_write_boost = L2ARC_WRITE_SIZE;	/* extra warmup write */
 unsigned long l2arc_headroom = L2ARC_HEADROOM;		/* # of dev writes */
@@ -3829,7 +3827,7 @@ arc_tempreserve_space(uint64_t reserve, uint64_t txg)
 
 	/*
 	 * Writes will, almost always, require additional memory allocations
-	 * in order to compress/encrypt/etc the data.  We therefor need to
+	 * in order to compress/encrypt/etc the data.  We therefore need to
 	 * make sure that there is sufficient available memory for this.
 	 */
 	if ((error = arc_memory_throttle(reserve, anon_size, txg)))

module/zfs/bptree.c

@@ -43,7 +43,7 @@
  * dsl_scan_sync. This allows the delete operation to finish without traversing
  * all the dataset's blocks.
  *
- * Note that while bt_begin and bt_end are only ever incremented in this code
+ * Note that while bt_begin and bt_end are only ever incremented in this code,
  * they are effectively reset to 0 every time the entire bptree is freed because
  * the bptree's object is destroyed and re-created.
  */

module/zfs/dnode.c

@@ -1804,14 +1804,16 @@ dnode_willuse_space(dnode_t *dn, int64_t space, dmu_tx_t *tx)
 }
 
 /*
- * This function scans a block at the indicated "level" looking for
+ * Scans a block at the indicated "level" looking for a hole or data,
- * a hole or data (depending on 'flags').  If level > 0, then we are
+ * depending on 'flags'.
- * scanning an indirect block looking at its pointers.  If level == 0,
+ *
- * then we are looking at a block of dnodes.  If we don't find what we
+ * If level > 0, then we are scanning an indirect block looking at its
- * are looking for in the block, we return ESRCH.  Otherwise, return
+ * pointers.  If level == 0, then we are looking at a block of dnodes.
- * with *offset pointing to the beginning (if searching forwards) or
+ *
- * end (if searching backwards) of the range covered by the block
+ * If we don't find what we are looking for in the block, we return ESRCH.
- * pointer we matched on (or dnode).
+ * Otherwise, return with *offset pointing to the beginning (if searching
+ * forwards) or end (if searching backwards) of the range covered by the
+ * block pointer we matched on (or dnode).
  *
  * The basic search algorithm used below by dnode_next_offset() is to
  * use this function to search up the block tree (widen the search) until

module/zfs/dnode_sync.c

@@ -302,7 +302,7 @@ free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks, int trunc,
 }
 
 /*
- * free_range: Traverse the indicated range of the provided file
+ * Traverse the indicated range of the provided file
  * and "free" all the blocks contained there.
  */
 static void
@@ -370,7 +370,7 @@ dnode_sync_free_range(dnode_t *dn, uint64_t blkid, uint64_t nblks, dmu_tx_t *tx)
 }
 
 /*
- * Try to kick all the dnodes dbufs out of the cache...
+ * Try to kick all the dnode's dbufs out of the cache...
  */
 void
 dnode_evict_dbufs(dnode_t *dn)

module/zfs/dsl_prop.c

@@ -380,7 +380,7 @@ dsl_prop_predict(dsl_dir_t *dd, const char *propname,
 
 /*
  * Unregister this callback.  Return 0 on success, ENOENT if ddname is
- * invalid, ENOMSG if no matching callback registered.
+ * invalid, or ENOMSG if no matching callback registered.
  */
 int
 dsl_prop_unregister(dsl_dataset_t *ds, const char *propname,

module/zfs/sa.c

@@ -110,6 +110,7 @@
  * location.
  *
  * Byteswap implications:
+ *
  * Since the SA attributes are not entirely self describing we can't do
  * the normal byteswap processing.  The special ZAP layout attribute and
  * attribute registration attributes define the byteswap function and the
@@ -188,7 +189,6 @@ sa_attr_reg_t sa_legacy_attrs[] = {
 };
 
 /*
- * ZPL legacy layout
  * This is only used for objects of type DMU_OT_ZNODE
  */
 sa_attr_type_t sa_legacy_zpl_layout[] = {
@@ -198,7 +198,6 @@ sa_attr_type_t sa_legacy_zpl_layout[] = {
 /*
  * Special dummy layout used for buffers with no attributes.
  */
-
 sa_attr_type_t sa_dummy_zpl_layout[] = { 0 };
 
 static int sa_legacy_attr_count = 16;

module/zfs/spa.c

@@ -4585,6 +4585,7 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
 
 /*
  * Detach a device from a mirror or replacing vdev.
+ *
  * If 'replace_done' is specified, only detach if the parent
  * is a replacing vdev.
  */
@@ -5242,11 +5243,9 @@ spa_vdev_remove_from_namespace(spa_t *spa, vdev_t *vd)
  * the spa_vdev_config_[enter/exit] functions which allow us to
  * grab and release the spa_config_lock while still holding the namespace
  * lock.  During each step the configuration is synced out.
- */
+ *
-
+ * Currently, this supports removing only hot spares, slogs, and level 2 ARC
-/*
+ * devices.
- * Remove a device from the pool.  Currently, this supports removing only hot
- * spares, slogs, and level 2 ARC devices.
  */
 int
 spa_vdev_remove(spa_t *spa, uint64_t guid, boolean_t unspare)
@@ -5356,7 +5355,7 @@ spa_vdev_remove(spa_t *spa, uint64_t guid, boolean_t unspare)
 
 /*
  * Find any device that's done replacing, or a vdev marked 'unspare' that's
- * current spared, so we can detach it.
+ * currently spared, so we can detach it.
  */
 static vdev_t *
 spa_vdev_resilver_done_hunt(vdev_t *vd)

module/zfs/spa_config.c

@@ -320,6 +320,7 @@ spa_config_set(spa_t *spa, nvlist_t *config)
 
 /*
  * Generate the pool's configuration based on the current in-core state.
+ *
  * We infer whether to generate a complete config or just one top-level config
  * based on whether vd is the root vdev.
  */

module/zfs/spa_misc.c

@@ -1288,7 +1288,7 @@ spa_freeze(spa_t *spa)
 
 /*
  * This is a stripped-down version of strtoull, suitable only for converting
- * lowercase hexidecimal numbers that don't overflow.
+ * lowercase hexadecimal numbers that don't overflow.
  */
 uint64_t
 strtonum(const char *str, char **nptr)

module/zfs/txg.c

@@ -636,7 +636,7 @@ txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
 	tx_state_t *tx = &dp->dp_tx;
 	hrtime_t start = gethrtime();
 
-	/* don't delay if this txg could transition to quiesing immediately */
+	/* don't delay if this txg could transition to quiescing immediately */
 	if (tx->tx_open_txg > txg ||
 	    tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
 		return;

module/zfs/vdev.c

@@ -966,9 +966,11 @@ vdev_probe_done(zio_t *zio)
 }
 
 /*
- * Determine whether this device is accessible by reading and writing
+ * Determine whether this device is accessible.
- * to several known locations: the pad regions of each vdev label
+ *
- * but the first (which we leave alone in case it contains a VTOC).
+ * Read and write to several known locations: the pad regions of each
+ * vdev label but the first, which we leave alone in case it contains
+ * a VTOC.
  */
 zio_t *
 vdev_probe(vdev_t *vd, zio_t *zio)
@@ -2202,10 +2204,12 @@ vdev_degrade(spa_t *spa, uint64_t guid, vdev_aux_t aux)
 }
 
 /*
- * Online the given vdev.  If 'unspare' is set, it implies two things.  First,
+ * Online the given vdev.
- * any attached spare device should be detached when the device finishes
+ *
- * resilvering.  Second, the online should be treated like a 'test' online case,
+ * If 'ZFS_ONLINE_UNSPARE' is set, it implies two things.  First, any attached
- * so no FMA events are generated if the device fails to open.
+ * spare device should be detached when the device finishes resilvering.
+ * Second, the online should be treated like a 'test' online case, so no FMA
+ * events are generated if the device fails to open.
  */
 int
 vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)

module/zfs/vdev_queue.c

@@ -37,13 +37,14 @@
 /*
  * These tunables are for performance analysis.
  */
-/*
+
- * zfs_vdev_max_pending is the maximum number of i/os concurrently
+/* The maximum number of I/Os concurrently pending to each device. */
- * pending to each device.  zfs_vdev_min_pending is the initial number
- * of i/os pending to each device (before it starts ramping up to
- * max_pending).
- */
 int zfs_vdev_max_pending = 10;
+
+/*
+ * The initial number of I/Os pending to each device, before it starts ramping
+ * up to zfs_vdev_max_pending.
+ */
 int zfs_vdev_min_pending = 4;
 
 /*

module/zfs/vdev_raidz.c

@@ -60,6 +60,7 @@
  *   o addition (+) is represented by a bitwise XOR
  *   o subtraction (-) is therefore identical to addition: A + B = A - B
  *   o multiplication of A by 2 is defined by the following bitwise expression:
+ *
  *	(A * 2)_7 = A_6
  *	(A * 2)_6 = A_5
  *	(A * 2)_5 = A_4
@@ -118,7 +119,7 @@ typedef struct raidz_map {
 	uint64_t rm_missingparity;	/* Count of missing parity devices */
 	uint64_t rm_firstdatacol;	/* First data column/parity count */
 	uint64_t rm_nskip;		/* Skipped sectors for padding */
-	uint64_t rm_skipstart;	/* Column index of padding start */
+	uint64_t rm_skipstart;		/* Column index of padding start */
 	void *rm_datacopy;		/* rm_asize-buffer of copied data */
 	uintptr_t rm_reports;		/* # of referencing checksum reports */
 	uint8_t	rm_freed;		/* map no longer has referencing ZIO */
@@ -158,10 +159,7 @@ typedef struct raidz_map {
  */
 int vdev_raidz_default_to_general;
 
-/*
+/* Powers of 2 in the Galois field defined above. */
- * These two tables represent powers and logs of 2 in the Galois field defined
- * above. These values were computed by repeatedly multiplying by 2 as above.
- */
 static const uint8_t vdev_raidz_pow2[256] = {
 	0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
 	0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26,
@@ -196,6 +194,7 @@ static const uint8_t vdev_raidz_pow2[256] = {
 	0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83,
 	0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01
 };
+/* Logs of 2 in the Galois field defined above. */
 static const uint8_t vdev_raidz_log2[256] = {
 	0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6,
 	0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b,

module/zfs/zfs_acl.c

@@ -1476,7 +1476,8 @@ zfs_acl_chmod(zfs_sb_t *zsb, uint64_t mode, zfs_acl_t *aclp)
 		zacep = (void *)((uintptr_t)zacep + abstract_size);
 		new_count++;
 		new_bytes += abstract_size;
-	} if (deny1) {
+	}
+	if (deny1) {
 		zfs_set_ace(aclp, zacep, deny1, DENY, -1, ACE_OWNER);
 		zacep = (void *)((uintptr_t)zacep + abstract_size);
 		new_count++;
@@ -1873,7 +1874,7 @@ zfs_acl_ids_overquota(zfs_sb_t *zsb, zfs_acl_ids_t *acl_ids)
 }
 
 /*
- * Retrieve a files ACL
+ * Retrieve a file's ACL
  */
 int
 zfs_getacl(znode_t *zp, vsecattr_t *vsecp, boolean_t skipaclchk, cred_t *cr)
@@ -2028,7 +2029,7 @@ zfs_vsec_2_aclp(zfs_sb_t *zsb, umode_t obj_mode,
 }
 
 /*
- * Set a files ACL
+ * Set a file's ACL
  */
 int
 zfs_setacl(znode_t *zp, vsecattr_t *vsecp, boolean_t skipaclchk, cred_t *cr)
@@ -2449,6 +2450,7 @@ slow:
 
 /*
  * Determine whether Access should be granted/denied.
+ *
  * The least priv subsytem is always consulted as a basic privilege
  * can define any form of access.
  */
@@ -2656,7 +2658,6 @@ zfs_delete_final_check(znode_t *zp, znode_t *dzp,
  * Determine whether Access should be granted/deny, without
  * consulting least priv subsystem.
  *
- *
  * The following chart is the recommended NFSv4 enforcement for
  * ability to delete an object.
  *

module/zfs/zfs_ioctl.c

@@ -290,9 +290,7 @@ zfs_is_bootfs(const char *name)
 }
 
 /*
- * zfs_earlier_version
+ * Return non-zero if the spa version is less than requested version.
- *
- *	Return non-zero if the spa version is less than requested version.
  */
 static int
 zfs_earlier_version(const char *name, int version)
@@ -310,8 +308,6 @@ zfs_earlier_version(const char *name, int version)
 }
 
 /*
- * zpl_earlier_version
- *
  * Return TRUE if the ZPL version is less than requested version.
  */
 static boolean_t
@@ -2942,10 +2938,10 @@ zfs_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
 
 /*
  * inputs:
- * createprops		list of properties requested by creator
- * default_zplver	zpl version to use if unspecified in createprops
- * fuids_ok		fuids allowed in this version of the spa?
  * os			parent objset pointer (NULL if root fs)
+ * fuids_ok		fuids allowed in this version of the spa?
+ * sa_ok		SAs allowed in this version of the spa?
+ * createprops		list of properties requested by creator
  *
  * outputs:
  * zplprops	values for the zplprops we attach to the master node object

module/zfs/zfs_log.c

@@ -212,9 +212,8 @@ zfs_log_fuid_domains(zfs_fuid_info_t *fuidp, void *start)
 }
 
 /*
- * zfs_log_create() is used to handle TX_CREATE, TX_CREATE_ATTR, TX_MKDIR,
+ * Handles TX_CREATE, TX_CREATE_ATTR, TX_MKDIR, TX_MKDIR_ATTR and
- * TX_MKDIR_ATTR and TX_MKXATTR
+ * TK_MKXATTR transactions.
- * transactions.
  *
  * TX_CREATE and TX_MKDIR are standard creates, but they may have FUID
  * domain information appended prior to the name.  In this case the
@@ -341,7 +340,7 @@ zfs_log_create(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 }
 
 /*
- * zfs_log_remove() handles both TX_REMOVE and TX_RMDIR transactions.
+ * Handles both TX_REMOVE and TX_RMDIR transactions.
  */
 void
 zfs_log_remove(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
@@ -365,7 +364,7 @@ zfs_log_remove(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 }
 
 /*
- * zfs_log_link() handles TX_LINK transactions.
+ * Handles TX_LINK transactions.
  */
 void
 zfs_log_link(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
@@ -388,7 +387,7 @@ zfs_log_link(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 }
 
 /*
- * zfs_log_symlink() handles TX_SYMLINK transactions.
+ * Handles TX_SYMLINK transactions.
  */
 void
 zfs_log_symlink(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
@@ -420,7 +419,7 @@ zfs_log_symlink(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 }
 
 /*
- * zfs_log_rename() handles TX_RENAME transactions.
+ * Handles TX_RENAME transactions.
  */
 void
 zfs_log_rename(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
@@ -446,7 +445,7 @@ zfs_log_rename(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 }
 
 /*
- * zfs_log_write() handles TX_WRITE transactions.
+ * Handles TX_WRITE transactions.
  */
 long zfs_immediate_write_sz = 32768;
 
@@ -525,7 +524,7 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 }
 
 /*
- * zfs_log_truncate() handles TX_TRUNCATE transactions.
+ * Handles TX_TRUNCATE transactions.
  */
 void
 zfs_log_truncate(zilog_t *zilog, dmu_tx_t *tx, int txtype,
@@ -548,7 +547,7 @@ zfs_log_truncate(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 }
 
 /*
- * zfs_log_setattr() handles TX_SETATTR transactions.
+ * Handles TX_SETATTR transactions.
  */
 void
 zfs_log_setattr(zilog_t *zilog, dmu_tx_t *tx, int txtype,
@@ -610,7 +609,7 @@ zfs_log_setattr(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 }
 
 /*
- * zfs_log_acl() handles TX_ACL transactions.
+ * Handles TX_ACL transactions.
  */
 void
 zfs_log_acl(zilog_t *zilog, dmu_tx_t *tx, znode_t *zp,

module/zfs/zfs_rlock.c

@@ -28,7 +28,7 @@
 
 /*
  * This file contains the code to implement file range locking in
- * ZFS, although there isn't much specific to ZFS (all that comes to mind
+ * ZFS, although there isn't much specific to ZFS (all that comes to mind is
  * support for growing the blocksize).
  *
  * Interface

module/zfs/zfs_sa.c

@@ -264,7 +264,7 @@ out:
 /*
  * I'm not convinced we should do any of this upgrade.
  * since the SA code can read both old/new znode formats
- * with probably little to know performance difference.
+ * with probably little to no performance difference.
  *
  * All new files will be created with the new format.
  */

module/zfs/zfs_vfsops.c

@@ -947,13 +947,12 @@ EXPORT_SYMBOL(zfs_unregister_callbacks);
 
 #ifdef HAVE_MLSLABEL
 /*
- * zfs_check_global_label:
+ * Check that the hex label string is appropriate for the dataset being
- *	Check that the hex label string is appropriate for the dataset
+ * mounted into the global_zone proper.
- *	being mounted into the global_zone proper.
  *
- *	Return an error if the hex label string is not default or
+ * Return an error if the hex label string is not default or
- *	admin_low/admin_high.  For admin_low labels, the corresponding
+ * admin_low/admin_high.  For admin_low labels, the corresponding
- *	dataset must be readonly.
+ * dataset must be readonly.
  */
 int
 zfs_check_global_label(const char *dsname, const char *hexsl)

module/zfs/zfs_vnops.c

@@ -123,7 +123,7 @@
  *  (5)	If the operation succeeded, generate the intent log entry for it
  *	before dropping locks.  This ensures that the ordering of events
  *	in the intent log matches the order in which they actually occurred.
- *      During ZIL replay the zfs_log_* functions will update the sequence
+ *	During ZIL replay the zfs_log_* functions will update the sequence
  *	number to indicate the zil transaction has replayed.
  *
  *  (6)	At the end of each vnode op, the DMU tx must always commit,
@@ -357,7 +357,7 @@ update_pages(struct inode *ip, int64_t start, int len,
  *		else we default from the dmu buffer.
  *
  * NOTE: We will always "break up" the IO into PAGESIZE uiomoves when
- *	the file is memory mapped.
+ *	 the file is memory mapped.
  */
 static int
 mappedread(struct inode *ip, int nbytes, uio_t *uio)
@@ -418,8 +418,7 @@ unsigned long zfs_read_chunk_size = 1024 * 1024; /* Tunable */
  *
  *	OUT:	uio	- updated offset and range, buffer filled.
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Side Effects:
  *	inode - atime updated if byte count > 0
@@ -1116,8 +1115,7 @@ EXPORT_SYMBOL(zfs_access);
  *
  *	OUT:	ipp	- inode of located entry, NULL if not found.
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	NA
@@ -1249,8 +1247,7 @@ EXPORT_SYMBOL(zfs_lookup);
  *
  *	OUT:	ipp	- inode of created or trunc'd entry.
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	dip - ctime|mtime updated if new entry created
@@ -1858,8 +1855,7 @@ EXPORT_SYMBOL(zfs_mkdir);
  *		cr	- credentials of caller.
  *		flags	- case flags
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	dip - ctime|mtime updated
@@ -3148,8 +3144,7 @@ zfs_rename_lock(znode_t *szp, znode_t *tdzp, znode_t *sdzp, zfs_zlock_t **zlpp)
  *		cr	- credentials of caller.
  *		flags	- case flags
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	sdip,tdip - ctime|mtime updated
@@ -3483,8 +3478,7 @@ EXPORT_SYMBOL(zfs_rename);
  *		cr	- credentials of caller.
  *		flags	- case flags
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	dip - ctime|mtime updated
@@ -4141,8 +4135,7 @@ zfs_fillpage(struct inode *ip, struct page *pl[], int nr_pages)
  *		pl	 - list of pages to read
  *		nr_pages - number of pages to read
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	vp - atime updated
@@ -4277,8 +4270,7 @@ convoff(struct inode *ip, flock64_t *lckdat, int  whence, offset_t offset)
  *		offset	- current file offset.
  *		cr	- credentials of caller [UNUSED].
  *
- *	RETURN:	0 if success
+ *	RETURN:	0 on success, error code on failure.
- *		error code if failure
  *
  * Timestamps:
  *	ip - ctime|mtime updated

module/zfs/zfs_znode.c

@@ -754,9 +754,8 @@ zfs_mknode(znode_t *dzp, vattr_t *vap, dmu_tx_t *tx, cred_t *cr,
 }
 
 /*
- * zfs_xvattr_set only updates the in-core attributes
+ * Update in-core attributes.  It is assumed the caller will be doing an
- * it is assumed the caller will be doing an sa_bulk_update
+ * sa_bulk_update to push the changes out.
- * to push the changes out
  */
 void
 zfs_xvattr_set(znode_t *zp, xvattr_t *xvap, dmu_tx_t *tx)
@@ -1183,8 +1182,7 @@ zfs_grow_blocksize(znode_t *zp, uint64_t size, dmu_tx_t *tx)
  *	IN:	zp	- znode of file to free data in.
  *		end	- new end-of-file
  *
- * 	RETURN:	0 if success
+ * 	RETURN:	0 on success, error code on failure
- *		error code if failure
  */
 static int
 zfs_extend(znode_t *zp, uint64_t end)
@@ -1261,8 +1259,7 @@ top:
  *		off	- start of section to free.
  *		len	- length of section to free.
  *
- *	RETURN:	0 if success
+ * 	RETURN:	0 on success, error code on failure
- *		error code if failure
  */
 static int
 zfs_free_range(znode_t *zp, uint64_t off, uint64_t len)
@@ -1300,8 +1297,7 @@ zfs_free_range(znode_t *zp, uint64_t off, uint64_t len)
  *	IN:	zp	- znode of file to free data in.
  *		end	- new end-of-file.
  *
- *	RETURN:	0 if success
+ * 	RETURN:	0 on success, error code on failure
- *		error code if failure
  */
 static int
 zfs_trunc(znode_t *zp, uint64_t end)
@@ -1374,8 +1370,7 @@ top:
  *		flag	- current file open mode flags.
  *		log	- TRUE if this action should be logged
  *
- *	RETURN:	0 if success
+ * 	RETURN:	0 on success, error code on failure
- *		error code if failure
  */
 int
 zfs_freesp(znode_t *zp, uint64_t off, uint64_t len, int flag, boolean_t log)

module/zfs/zil.c

@@ -88,9 +88,9 @@ zil_stats_t zil_stats = {
 static kstat_t *zil_ksp;
 
 /*
- * This global ZIL switch affects all pools
+ * Disable intent logging replay.  This global ZIL switch affects all pools.
  */
-int zil_replay_disable = 0;    /* disable intent logging replay */
+int zil_replay_disable = 0;
 
 /*
  * Tunable parameter for debugging or performance analysis.  Setting
@@ -922,6 +922,7 @@ zil_lwb_write_init(zilog_t *zilog, lwb_t *lwb)
 
 /*
  * Define a limited set of intent log block sizes.
+ *
  * These must be a multiple of 4KB. Note only the amount used (again
  * aligned to 4KB) actually gets written. However, we can't always just
  * allocate SPA_MAXBLOCKSIZE as the slog space could be exhausted.