1 files changed, 233 insertions, 52 deletions

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index aadfce6681ee..6a7096422295 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -41,6 +41,9 @@
 #include "xfs_utils.h"
 #include "xfs_iomap.h"
 #include "xfs_trace.h"
+#include "xfs_icache.h"
+#include "xfs_dquot_item.h"
+#include "xfs_dquot.h"
 
 
 #define XFS_WRITEIO_ALIGN(mp,off)	(((off) >> mp->m_writeio_log) \
@@ -281,11 +284,20 @@ xfs_iomap_eof_want_preallocate(
 		return 0;
 
 	/*
+	 * If the file is smaller than the minimum prealloc and we are using
+	 * dynamic preallocation, don't do any preallocation at all as it is
+	 * likely this is the only write to the file that is going to be done.
+	 */
+	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
+	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks))
+		return 0;
+
+	/*
 	 * If there are any real blocks past eof, then don't
 	 * do any speculative allocation.
 	 */
 	start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
-	count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
+	count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 	while (count_fsb > 0) {
 		imaps = nimaps;
 		firstblock = NULLFSBLOCK;
@@ -310,6 +322,121 @@ xfs_iomap_eof_want_preallocate(
 }
 
 /*
+ * Determine the initial size of the preallocation. We are beyond the current
+ * EOF here, but we need to take into account whether this is a sparse write or
+ * an extending write when determining the preallocation size.  Hence we need to
+ * look up the extent that ends at the current write offset and use the result
+ * to determine the preallocation size.
+ *
+ * If the extent is a hole, then preallocation is essentially disabled.
+ * Otherwise we take the size of the preceeding data extent as the basis for the
+ * preallocation size. If the size of the extent is greater than half the
+ * maximum extent length, then use the current offset as the basis. This ensures
+ * that for large files the preallocation size always extends to MAXEXTLEN
+ * rather than falling short due to things like stripe unit/width alignment of
+ * real extents.
+ */
+STATIC xfs_fsblock_t
+xfs_iomap_eof_prealloc_initial_size(
+	struct xfs_mount	*mp,
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	xfs_bmbt_irec_t		*imap,
+	int			nimaps)
+{
+	xfs_fileoff_t   start_fsb;
+	int		imaps = 1;
+	int		error;
+
+	ASSERT(nimaps >= imaps);
+
+	/* if we are using a specific prealloc size, return now */
+	if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
+		return 0;
+
+	/* If the file is small, then use the minimum prealloc */
+	if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign))
+		return 0;
+
+	/*
+	 * As we write multiple pages, the offset will always align to the
+	 * start of a page and hence point to a hole at EOF. i.e. if the size is
+	 * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096)
+	 * will return FSB 1. Hence if there are blocks in the file, we want to
+	 * point to the block prior to the EOF block and not the hole that maps
+	 * directly at @offset.
+	 */
+	start_fsb = XFS_B_TO_FSB(mp, offset);
+	if (start_fsb)
+		start_fsb--;
+	error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE);
+	if (error)
+		return 0;
+
+	ASSERT(imaps == 1);
+	if (imap[0].br_startblock == HOLESTARTBLOCK)
+		return 0;
+	if (imap[0].br_blockcount <= (MAXEXTLEN >> 1))
+		return imap[0].br_blockcount << 1;
+	return XFS_B_TO_FSB(mp, offset);
+}
+
+STATIC bool
+xfs_quota_need_throttle(
+	struct xfs_inode *ip,
+	int type,
+	xfs_fsblock_t alloc_blocks)
+{
+	struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
+
+	if (!dq || !xfs_this_quota_on(ip->i_mount, type))
+		return false;
+
+	/* no hi watermark, no throttle */
+	if (!dq->q_prealloc_hi_wmark)
+		return false;
+
+	/* under the lo watermark, no throttle */
+	if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark)
+		return false;
+
+	return true;
+}
+
+STATIC void
+xfs_quota_calc_throttle(
+	struct xfs_inode *ip,
+	int type,
+	xfs_fsblock_t *qblocks,
+	int *qshift)
+{
+	int64_t freesp;
+	int shift = 0;
+	struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
+
+	/* over hi wmark, squash the prealloc completely */
+	if (dq->q_res_bcount >= dq->q_prealloc_hi_wmark) {
+		*qblocks = 0;
+		return;
+	}
+
+	freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount;
+	if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) {
+		shift = 2;
+		if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT])
+			shift += 2;
+		if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT])
+			shift += 2;
+	}
+
+	/* only overwrite the throttle values if we are more aggressive */
+	if ((freesp >> shift) < (*qblocks >> *qshift)) {
+		*qblocks = freesp;
+		*qshift = shift;
+	}
+}
+
+/*
  * If we don't have a user specified preallocation size, dynamically increase
  * the preallocation size as the size of the file grows. Cap the maximum size
  * at a single extent or less if the filesystem is near full. The closer the
@@ -318,43 +445,95 @@ xfs_iomap_eof_want_preallocate(
 STATIC xfs_fsblock_t
 xfs_iomap_prealloc_size(
 	struct xfs_mount	*mp,
-	struct xfs_inode	*ip)
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	struct xfs_bmbt_irec	*imap,
+	int			nimaps)
 {
 	xfs_fsblock_t		alloc_blocks = 0;
+	int			shift = 0;
+	int64_t			freesp;
+	xfs_fsblock_t		qblocks;
+	int			qshift = 0;
 
-	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
-		int shift = 0;
-		int64_t freesp;
+	alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset,
+							   imap, nimaps);
+	if (!alloc_blocks)
+		goto check_writeio;
+	qblocks = alloc_blocks;
 
-		/*
-		 * rounddown_pow_of_two() returns an undefined result
-		 * if we pass in alloc_blocks = 0. Hence the "+ 1" to
-		 * ensure we always pass in a non-zero value.
-		 */
-		alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
-		alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
-					rounddown_pow_of_two(alloc_blocks));
-
-		xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
-		freesp = mp->m_sb.sb_fdblocks;
-		if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
-			shift = 2;
-			if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
-				shift++;
-			if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
-				shift++;
-			if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
-				shift++;
-			if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
-				shift++;
-		}
-		if (shift)
-			alloc_blocks >>= shift;
+	/*
+	 * MAXEXTLEN is not a power of two value but we round the prealloc down
+	 * to the nearest power of two value after throttling. To prevent the
+	 * round down from unconditionally reducing the maximum supported prealloc
+	 * size, we round up first, apply appropriate throttling, round down and
+	 * cap the value to MAXEXTLEN.
+	 */
+	alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN),
+				       alloc_blocks);
+
+	xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
+	freesp = mp->m_sb.sb_fdblocks;
+	if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
+		shift = 2;
+		if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
+			shift++;
+		if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
+			shift++;
+		if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
+			shift++;
+		if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
+			shift++;
 	}
 
+	/*
+	 * Check each quota to cap the prealloc size and provide a shift
+	 * value to throttle with.
+	 */
+	if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks))
+		xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift);
+	if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks))
+		xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift);
+	if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks))
+		xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift);
+
+	/*
+	 * The final prealloc size is set to the minimum of free space available
+	 * in each of the quotas and the overall filesystem.
+	 *
+	 * The shift throttle value is set to the maximum value as determined by
+	 * the global low free space values and per-quota low free space values.
+	 */
+	alloc_blocks = MIN(alloc_blocks, qblocks);
+	shift = MAX(shift, qshift);
+
+	if (shift)
+		alloc_blocks >>= shift;
+	/*
+	 * rounddown_pow_of_two() returns an undefined result if we pass in
+	 * alloc_blocks = 0.
+	 */
+	if (alloc_blocks)
+		alloc_blocks = rounddown_pow_of_two(alloc_blocks);
+	if (alloc_blocks > MAXEXTLEN)
+		alloc_blocks = MAXEXTLEN;
+
+	/*
+	 * If we are still trying to allocate more space than is
+	 * available, squash the prealloc hard. This can happen if we
+	 * have a large file on a small filesystem and the above
+	 * lowspace thresholds are smaller than MAXEXTLEN.
+	 */
+	while (alloc_blocks && alloc_blocks >= freesp)
+		alloc_blocks >>= 4;
+
+check_writeio:
 	if (alloc_blocks < mp->m_writeio_blocks)
 		alloc_blocks = mp->m_writeio_blocks;
 
+	trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
+				      mp->m_writeio_blocks);
+
 	return alloc_blocks;
 }
 
@@ -373,7 +552,7 @@ xfs_iomap_write_delay(
 	xfs_extlen_t	extsz;
 	int		nimaps;
 	xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
-	int		prealloc, flushed = 0;
+	int		prealloc;
 	int		error;
 
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
@@ -389,7 +568,6 @@ xfs_iomap_write_delay(
 	extsz = xfs_get_extsz_hint(ip);
 	offset_fsb = XFS_B_TO_FSBT(mp, offset);
 
-
 	error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
 				imap, XFS_WRITE_IMAPS, &prealloc);
 	if (error)
@@ -397,7 +575,10 @@ xfs_iomap_write_delay(
 
 retry:
 	if (prealloc) {
-		xfs_fsblock_t	alloc_blocks = xfs_iomap_prealloc_size(mp, ip);
+		xfs_fsblock_t	alloc_blocks;
+
+		alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap,
+						       XFS_WRITE_IMAPS);
 
 		aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
 		ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
@@ -416,8 +597,8 @@ retry:
 	 * Make sure preallocation does not create extents beyond the range we
 	 * actually support in this filesystem.
 	 */
-	if (last_fsb > XFS_B_TO_FSB(mp, mp->m_maxioffset))
-		last_fsb = XFS_B_TO_FSB(mp, mp->m_maxioffset);
+	if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
+		last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 
 	ASSERT(last_fsb > offset_fsb);
 
@@ -434,31 +615,29 @@ retry:
 	}
 
 	/*
-	 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT.  For
-	 * ENOSPC, * flush all other inodes with delalloc blocks to free up
-	 * some of the excess reserved metadata space. For both cases, retry
+	 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
 	 * without EOF preallocation.
 	 */
 	if (nimaps == 0) {
 		trace_xfs_delalloc_enospc(ip, offset, count);
-		if (flushed)
-			return XFS_ERROR(error ? error : ENOSPC);
-
-		if (error == ENOSPC) {
-			xfs_iunlock(ip, XFS_ILOCK_EXCL);
-			xfs_flush_inodes(ip);
-			xfs_ilock(ip, XFS_ILOCK_EXCL);
+		if (prealloc) {
+			prealloc = 0;
+			error = 0;
+			goto retry;
 		}
-
-		flushed = 1;
-		error = 0;
-		prealloc = 0;
-		goto retry;
+		return XFS_ERROR(error ? error : ENOSPC);
 	}
 
 	if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
 		return xfs_alert_fsblock_zero(ip, &imap[0]);
 
+	/*
+	 * Tag the inode as speculatively preallocated so we can reclaim this
+	 * space on demand, if necessary.
+	 */
+	if (prealloc)
+		xfs_inode_set_eofblocks_tag(ip);
+
 	*ret_imap = imap[0];
 	return 0;
 }
@@ -584,7 +763,9 @@ xfs_iomap_write_allocate(
 			 * pointer that the caller gave to us.
 			 */
 			error = xfs_bmapi_write(tp, ip, map_start_fsb,
-						count_fsb, 0, &first_block, 1,
+						count_fsb,
+						XFS_BMAPI_STACK_SWITCH,
+						&first_block, 1,
 						imap, &nimaps, &free_list);
 			if (error)
 				goto trans_cancel;
@@ -680,9 +861,9 @@ xfs_iomap_write_unwritten(
 		 * the same inode that we complete here and might deadlock
 		 * on the iolock.
 		 */
-		xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+		sb_start_intwrite(mp->m_super);
 		tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
-		tp->t_flags |= XFS_TRANS_RESERVE;
+		tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
 		error = xfs_trans_reserve(tp, resblks,
 				XFS_WRITE_LOG_RES(mp), 0,
 				XFS_TRANS_PERM_LOG_RES,