xfs: convert bulkstat to new iwalk infrastructure

Create a new ibulk structure incore to help us deal with bulk inode stat
state tracking and then convert the bulkstat code to use the new iwalk
iterator.  This disentangles inode walking from bulk stat control for
simpler code and enables us to isolate the formatter functions to the
ioctl handling code.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

1 files changed, 132 insertions, 296 deletions

diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index 72af0c8cbc92..118ff1b686c1 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -14,46 +14,66 @@
 #include "xfs_btree.h"
 #include "xfs_ialloc.h"
 #include "xfs_ialloc_btree.h"
+#include "xfs_iwalk.h"
 #include "xfs_itable.h"
 #include "xfs_error.h"
 #include "xfs_icache.h"
 #include "xfs_health.h"
-#include "xfs_iwalk.h"
 
 /*
- * Return stat information for one inode.
- * Return 0 if ok, else errno.
+ * Bulk Stat
+ * =========
+ *
+ * Use the inode walking functions to fill out struct xfs_bstat for every
+ * allocated inode, then pass the stat information to some externally provided
+ * iteration function.
  */
-int
+
+struct xfs_bstat_chunk {
+	bulkstat_one_fmt_pf	formatter;
+	struct xfs_ibulk	*breq;
+	struct xfs_bstat	*buf;
+};
+
+/*
+ * Fill out the bulkstat info for a single inode and report it somewhere.
+ *
+ * bc->breq->lastino is effectively the inode cursor as we walk through the
+ * filesystem.  Therefore, we update it any time we need to move the cursor
+ * forward, regardless of whether or not we're sending any bstat information
+ * back to userspace.  If the inode is internal metadata or, has been freed
+ * out from under us, we just simply keep going.
+ *
+ * However, if any other type of error happens we want to stop right where we
+ * are so that userspace will call back with exact number of the bad inode and
+ * we can send back an error code.
+ *
+ * Note that if the formatter tells us there's no space left in the buffer we
+ * move the cursor forward and abort the walk.
+ */
+STATIC int
 xfs_bulkstat_one_int(
-	struct xfs_mount	*mp,		/* mount point for filesystem */
-	xfs_ino_t		ino,		/* inode to get data for */
-	void __user		*buffer,	/* buffer to place output in */
-	int			ubsize,		/* size of buffer */
-	bulkstat_one_fmt_pf	formatter,	/* formatter, copy to user */
-	int			*ubused,	/* bytes used by me */
-	int			*stat)		/* BULKSTAT_RV_... */
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_ino_t		ino,
+	struct xfs_bstat_chunk	*bc)
 {
 	struct xfs_icdinode	*dic;		/* dinode core info pointer */
 	struct xfs_inode	*ip;		/* incore inode pointer */
 	struct inode		*inode;
-	struct xfs_bstat	*buf;		/* return buffer */
-	int			error = 0;	/* error value */
+	struct xfs_bstat	*buf = bc->buf;
+	int			error = -EINVAL;
 
-	*stat = BULKSTAT_RV_NOTHING;
+	if (xfs_internal_inum(mp, ino))
+		goto out_advance;
 
-	if (!buffer || xfs_internal_inum(mp, ino))
-		return -EINVAL;
-
-	buf = kmem_zalloc(sizeof(*buf), KM_SLEEP | KM_MAYFAIL);
-	if (!buf)
-		return -ENOMEM;
-
-	error = xfs_iget(mp, NULL, ino,
+	error = xfs_iget(mp, tp, ino,
 			 (XFS_IGET_DONTCACHE | XFS_IGET_UNTRUSTED),
 			 XFS_ILOCK_SHARED, &ip);
+	if (error == -ENOENT || error == -EINVAL)
+		goto out_advance;
 	if (error)
-		goto out_free;
+		goto out;
 
 	ASSERT(ip != NULL);
 	ASSERT(ip->i_imap.im_blkno != 0);
@@ -118,43 +138,54 @@ xfs_bulkstat_one_int(
 	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 	xfs_irele(ip);
 
-	error = formatter(buffer, ubsize, ubused, buf);
-	if (!error)
-		*stat = BULKSTAT_RV_DIDONE;
+	error = bc->formatter(bc->breq, buf);
+	if (error == XFS_IBULK_ABORT)
+		goto out_advance;
+	if (error)
+		goto out;
 
- out_free:
-	kmem_free(buf);
+out_advance:
+	/*
+	 * Advance the cursor to the inode that comes after the one we just
+	 * looked at.  We want the caller to move along if the bulkstat
+	 * information was copied successfully; if we tried to grab the inode
+	 * but it's no longer allocated; or if it's internal metadata.
+	 */
+	bc->breq->startino = ino + 1;
+out:
 	return error;
 }
 
-/* Return 0 on success or positive error */
-STATIC int
-xfs_bulkstat_one_fmt(
-	void			__user *ubuffer,
-	int			ubsize,
-	int			*ubused,
-	const xfs_bstat_t	*buffer)
-{
-	if (ubsize < sizeof(*buffer))
-		return -ENOMEM;
-	if (copy_to_user(ubuffer, buffer, sizeof(*buffer)))
-		return -EFAULT;
-	if (ubused)
-		*ubused = sizeof(*buffer);
-	return 0;
-}
-
+/* Bulkstat a single inode. */
 int
 xfs_bulkstat_one(
-	xfs_mount_t	*mp,		/* mount point for filesystem */
-	xfs_ino_t	ino,		/* inode number to get data for */
-	void		__user *buffer,	/* buffer to place output in */
-	int		ubsize,		/* size of buffer */
-	int		*ubused,	/* bytes used by me */
-	int		*stat)		/* BULKSTAT_RV_... */
+	struct xfs_ibulk	*breq,
+	bulkstat_one_fmt_pf	formatter)
 {
-	return xfs_bulkstat_one_int(mp, ino, buffer, ubsize,
-				    xfs_bulkstat_one_fmt, ubused, stat);
+	struct xfs_bstat_chunk	bc = {
+		.formatter	= formatter,
+		.breq		= breq,
+	};
+	int			error;
+
+	ASSERT(breq->icount == 1);
+
+	bc.buf = kmem_zalloc(sizeof(struct xfs_bstat), KM_SLEEP | KM_MAYFAIL);
+	if (!bc.buf)
+		return -ENOMEM;
+
+	error = xfs_bulkstat_one_int(breq->mp, NULL, breq->startino, &bc);
+
+	kmem_free(bc.buf);
+
+	/*
+	 * If we reported one inode to userspace then we abort because we hit
+	 * the end of the buffer.  Don't leak that back to userspace.
+	 */
+	if (error == XFS_IWALK_ABORT)
+		error = 0;
+
+	return error;
 }
 
 /*
@@ -250,256 +281,69 @@ xfs_bulkstat_grab_ichunk(
 
 #define XFS_BULKSTAT_UBLEFT(ubleft)	((ubleft) >= statstruct_size)
 
-struct xfs_bulkstat_agichunk {
-	char		__user **ac_ubuffer;/* pointer into user's buffer */
-	int		ac_ubleft;	/* bytes left in user's buffer */
-	int		ac_ubelem;	/* spaces used in user's buffer */
-};
-
-/*
- * Process inodes in chunk with a pointer to a formatter function
- * that will iget the inode and fill in the appropriate structure.
- */
 static int
-xfs_bulkstat_ag_ichunk(
-	struct xfs_mount		*mp,
-	xfs_agnumber_t			agno,
-	struct xfs_inobt_rec_incore	*irbp,
-	bulkstat_one_pf			formatter,
-	size_t				statstruct_size,
-	struct xfs_bulkstat_agichunk	*acp,
-	xfs_agino_t			*last_agino)
+xfs_bulkstat_iwalk(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_ino_t		ino,
+	void			*data)
 {
-	char				__user **ubufp = acp->ac_ubuffer;
-	int				chunkidx;
-	int				error = 0;
-	xfs_agino_t			agino = irbp->ir_startino;
-
-	for (chunkidx = 0; chunkidx < XFS_INODES_PER_CHUNK;
-	     chunkidx++, agino++) {
-		int		fmterror;
-		int		ubused;
-
-		/* inode won't fit in buffer, we are done */
-		if (acp->ac_ubleft < statstruct_size)
-			break;
-
-		/* Skip if this inode is free */
-		if (XFS_INOBT_MASK(chunkidx) & irbp->ir_free)
-			continue;
-
-		/* Get the inode and fill in a single buffer */
-		ubused = statstruct_size;
-		error = formatter(mp, XFS_AGINO_TO_INO(mp, agno, agino),
-				  *ubufp, acp->ac_ubleft, &ubused, &fmterror);
-
-		if (fmterror == BULKSTAT_RV_GIVEUP ||
-		    (error && error != -ENOENT && error != -EINVAL)) {
-			acp->ac_ubleft = 0;
-			ASSERT(error);
-			break;
-		}
-
-		/* be careful not to leak error if at end of chunk */
-		if (fmterror == BULKSTAT_RV_NOTHING || error) {
-			error = 0;
-			continue;
-		}
-
-		*ubufp += ubused;
-		acp->ac_ubleft -= ubused;
-		acp->ac_ubelem++;
-	}
-
-	/*
-	 * Post-update *last_agino. At this point, agino will always point one
-	 * inode past the last inode we processed successfully. Hence we
-	 * substract that inode when setting the *last_agino cursor so that we
-	 * return the correct cookie to userspace. On the next bulkstat call,
-	 * the inode under the lastino cookie will be skipped as we have already
-	 * processed it here.
-	 */
-	*last_agino = agino - 1;
+	int			error;
 
+	error = xfs_bulkstat_one_int(mp, tp, ino, data);
+	/* bulkstat just skips over missing inodes */
+	if (error == -ENOENT || error == -EINVAL)
+		return 0;
 	return error;
 }
 
 /*
- * Return stat information in bulk (by-inode) for the filesystem.
+ * Check the incoming lastino parameter.
+ *
+ * We allow any inode value that could map to physical space inside the
+ * filesystem because if there are no inodes there, bulkstat moves on to the
+ * next chunk.  In other words, the magic agino value of zero takes us to the
+ * first chunk in the AG, and an agino value past the end of the AG takes us to
+ * the first chunk in the next AG.
+ *
+ * Therefore we can end early if the requested inode is beyond the end of the
+ * filesystem or doesn't map properly.
  */
-int					/* error status */
-xfs_bulkstat(
-	xfs_mount_t		*mp,	/* mount point for filesystem */
-	xfs_ino_t		*lastinop, /* last inode returned */
-	int			*ubcountp, /* size of buffer/count returned */
-	bulkstat_one_pf		formatter, /* func that'd fill a single buf */
-	size_t			statstruct_size, /* sizeof struct filling */
-	char			__user *ubuffer, /* buffer with inode stats */
-	int			*done)	/* 1 if there are more stats to get */
+static inline bool
+xfs_bulkstat_already_done(
+	struct xfs_mount	*mp,
+	xfs_ino_t		startino)
 {
-	xfs_buf_t		*agbp;	/* agi header buffer */
-	xfs_agino_t		agino;	/* inode # in allocation group */
-	xfs_agnumber_t		agno;	/* allocation group number */
-	xfs_btree_cur_t		*cur;	/* btree cursor for ialloc btree */
-	xfs_inobt_rec_incore_t	*irbuf;	/* start of irec buffer */
-	int			nirbuf;	/* size of irbuf */
-	int			ubcount; /* size of user's buffer */
-	struct xfs_bulkstat_agichunk ac;
-	int			error = 0;
+	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, startino);
+	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, startino);
 
-	/*
-	 * Get the last inode value, see if there's nothing to do.
-	 */
-	agno = XFS_INO_TO_AGNO(mp, *lastinop);
-	agino = XFS_INO_TO_AGINO(mp, *lastinop);
-	if (agno >= mp->m_sb.sb_agcount ||
-	    *lastinop != XFS_AGINO_TO_INO(mp, agno, agino)) {
-		*done = 1;
-		*ubcountp = 0;
-		return 0;
-	}
+	return agno >= mp->m_sb.sb_agcount ||
+	       startino != XFS_AGINO_TO_INO(mp, agno, agino);
+}
 
-	ubcount = *ubcountp; /* statstruct's */
-	ac.ac_ubuffer = &ubuffer;
-	ac.ac_ubleft = ubcount * statstruct_size; /* bytes */;
-	ac.ac_ubelem = 0;
+/* Return stat information in bulk (by-inode) for the filesystem. */
+int
+xfs_bulkstat(
+	struct xfs_ibulk	*breq,
+	bulkstat_one_fmt_pf	formatter)
+{
+	struct xfs_bstat_chunk	bc = {
+		.formatter	= formatter,
+		.breq		= breq,
+	};
+	int			error;
 
-	*ubcountp = 0;
-	*done = 0;
+	if (xfs_bulkstat_already_done(breq->mp, breq->startino))
+		return 0;
 
-	irbuf = kmem_zalloc_large(PAGE_SIZE * 4, KM_SLEEP);
-	if (!irbuf)
+	bc.buf = kmem_zalloc(sizeof(struct xfs_bstat), KM_SLEEP | KM_MAYFAIL);
+	if (!bc.buf)
 		return -ENOMEM;
-	nirbuf = (PAGE_SIZE * 4) / sizeof(*irbuf);
-
-	/*
-	 * Loop over the allocation groups, starting from the last
-	 * inode returned; 0 means start of the allocation group.
-	 */
-	while (agno < mp->m_sb.sb_agcount) {
-		struct xfs_inobt_rec_incore	*irbp = irbuf;
-		struct xfs_inobt_rec_incore	*irbufend = irbuf + nirbuf;
-		bool				end_of_ag = false;
-		int				icount = 0;
-		int				stat;
-
-		error = xfs_ialloc_read_agi(mp, NULL, agno, &agbp);
-		if (error)
-			break;
-		/*
-		 * Allocate and initialize a btree cursor for ialloc btree.
-		 */
-		cur = xfs_inobt_init_cursor(mp, NULL, agbp, agno,
-					    XFS_BTNUM_INO);
-		if (agino > 0) {
-			/*
-			 * In the middle of an allocation group, we need to get
-			 * the remainder of the chunk we're in.
-			 */
-			struct xfs_inobt_rec_incore	r;
-
-			error = xfs_bulkstat_grab_ichunk(cur, agino, &icount, &r);
-			if (error)
-				goto del_cursor;
-			if (icount) {
-				irbp->ir_startino = r.ir_startino;
-				irbp->ir_holemask = r.ir_holemask;
-				irbp->ir_count = r.ir_count;
-				irbp->ir_freecount = r.ir_freecount;
-				irbp->ir_free = r.ir_free;
-				irbp++;
-			}
-			/* Increment to the next record */
-			error = xfs_btree_increment(cur, 0, &stat);
-		} else {
-			/* Start of ag.  Lookup the first inode chunk */
-			error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &stat);
-		}
-		if (error || stat == 0) {
-			end_of_ag = true;
-			goto del_cursor;
-		}
-
-		/*
-		 * Loop through inode btree records in this ag,
-		 * until we run out of inodes or space in the buffer.
-		 */
-		while (irbp < irbufend && icount < ubcount) {
-			struct xfs_inobt_rec_incore	r;
-
-			error = xfs_inobt_get_rec(cur, &r, &stat);
-			if (error || stat == 0) {
-				end_of_ag = true;
-				goto del_cursor;
-			}
-
-			/*
-			 * If this chunk has any allocated inodes, save it.
-			 * Also start read-ahead now for this chunk.
-			 */
-			if (r.ir_freecount < r.ir_count) {
-				xfs_bulkstat_ichunk_ra(mp, agno, &r);
-				irbp->ir_startino = r.ir_startino;
-				irbp->ir_holemask = r.ir_holemask;
-				irbp->ir_count = r.ir_count;
-				irbp->ir_freecount = r.ir_freecount;
-				irbp->ir_free = r.ir_free;
-				irbp++;
-				icount += r.ir_count - r.ir_freecount;
-			}
-			error = xfs_btree_increment(cur, 0, &stat);
-			if (error || stat == 0) {
-				end_of_ag = true;
-				goto del_cursor;
-			}
-			cond_resched();
-		}
-
-		/*
-		 * Drop the btree buffers and the agi buffer as we can't hold any
-		 * of the locks these represent when calling iget. If there is a
-		 * pending error, then we are done.
-		 */
-del_cursor:
-		xfs_btree_del_cursor(cur, error);
-		xfs_buf_relse(agbp);
-		if (error)
-			break;
-		/*
-		 * Now format all the good inodes into the user's buffer. The
-		 * call to xfs_bulkstat_ag_ichunk() sets up the agino pointer
-		 * for the next loop iteration.
-		 */
-		irbufend = irbp;
-		for (irbp = irbuf;
-		     irbp < irbufend && ac.ac_ubleft >= statstruct_size;
-		     irbp++) {
-			error = xfs_bulkstat_ag_ichunk(mp, agno, irbp,
-					formatter, statstruct_size, &ac,
-					&agino);
-			if (error)
-				break;
 
-			cond_resched();
-		}
+	error = xfs_iwalk(breq->mp, NULL, breq->startino, xfs_bulkstat_iwalk,
+			breq->icount, &bc);
 
-		/*
-		 * If we've run out of space or had a formatting error, we
-		 * are now done
-		 */
-		if (ac.ac_ubleft < statstruct_size || error)
-			break;
-
-		if (end_of_ag) {
-			agno++;
-			agino = 0;
-		}
-	}
-	/*
-	 * Done, we're either out of filesystem or space to put the data.
-	 */
-	kmem_free(irbuf);
-	*ubcountp = ac.ac_ubelem;
+	kmem_free(bc.buf);
 
 	/*
 	 * We found some inodes, so clear the error status and return them.
@@ -508,17 +352,9 @@ del_cursor:
 	 * triggered again and propagated to userspace as there will be no
 	 * formatted inodes in the buffer.
 	 */
-	if (ac.ac_ubelem)
+	if (breq->ocount > 0)
 		error = 0;
 
-	/*
-	 * If we ran out of filesystem, lastino will point off the end of
-	 * the filesystem so the next call will return immediately.
-	 */
-	*lastinop = XFS_AGINO_TO_INO(mp, agno, agino);
-	if (agno >= mp->m_sb.sb_agcount)
-		*done = 1;
-
 	return error;
 }