svn commit: r295494 - head/sys/fs/ext2fs

[Pedro F. Giffuni]

Author: pfg
Date: Thu Feb 11 00:34:11 2016
New Revision: 295494
URL: https://svnweb.freebsd.org/changeset/base/295494

Log:
  Ext4: fix handling of files with sparse blocks before extent's index.
  
  This is ongoing work from Damjan Jovanovic to improve ext4 read support
  with sparse files:
  
  Keep track of the first and last block in each extent as it descends down
  the extent tree, thus being able to work out that some blocks are sparse
  earlier. This solves an issue on r293680.
  
  In ext4_bmapext() start supporting the runb parameter, which appears to be
  the number of adjacent blocks prior to the block being converted in the
  same way that runp is the number of blocks after, speding up random access
  to mmaped files.
  
  PR:	206652

Modified:
  head/sys/fs/ext2fs/ext2_bmap.c
  head/sys/fs/ext2fs/ext2_extents.c

Modified: head/sys/fs/ext2fs/ext2_bmap.c
==============================================================================
--- head/sys/fs/ext2fs/ext2_bmap.c	Thu Feb 11 00:30:51 2016	(r295493)
+++ head/sys/fs/ext2fs/ext2_bmap.c	Thu Feb 11 00:34:11 2016	(r295494)
@@ -114,6 +114,8 @@ ext4_bmapext(struct vnode *vp, int32_t b
 		if (runp != NULL)
 			*runp = path.ep_sparse_ext.e_len -
 			    (lbn - path.ep_sparse_ext.e_blk) - 1;
+		if (runb != NULL)
+			*runb = lbn - path.ep_sparse_ext.e_blk;
 	} else {
 		ep = path.ep_ext;
 		if (ep == NULL)
@@ -127,6 +129,8 @@ ext4_bmapext(struct vnode *vp, int32_t b
 
 			if (runp != NULL)
 				*runp = ep->e_len - (lbn - ep->e_blk) - 1;
+			if (runb != NULL)
+				*runb = lbn - ep->e_blk;
 		}
 	}
 

Modified: head/sys/fs/ext2fs/ext2_extents.c
==============================================================================
--- head/sys/fs/ext2fs/ext2_extents.c	Thu Feb 11 00:30:51 2016	(r295493)
+++ head/sys/fs/ext2fs/ext2_extents.c	Thu Feb 11 00:34:11 2016	(r295494)
@@ -43,14 +43,17 @@
 #include <fs/ext2fs/ext2_extents.h>
 #include <fs/ext2fs/ext2_extern.h>
 
-static void ext4_ext_binsearch_index(struct inode *ip, struct ext4_extent_path
-		*path, daddr_t lbn)
+static int
+ext4_ext_binsearch_index(struct inode *ip, struct ext4_extent_path *path,
+		daddr_t lbn, daddr_t *first_lbn, daddr_t *last_lbn)
 {
 	struct ext4_extent_header *ehp = path->ep_header;
-	struct ext4_extent_index *l, *r, *m;
+	struct ext4_extent_index *first, *last, *l, *r, *m;
 
-	l = (struct ext4_extent_index *)(char *)(ehp + 1);
-	r = (struct ext4_extent_index *)(char *)(ehp + 1) + ehp->eh_ecount - 1;
+	first = (struct ext4_extent_index *)(char *)(ehp + 1);
+	last = first + ehp->eh_ecount - 1;
+	l = first;
+	r = last;
 	while (l <= r) {
 		m = l + (r - l) / 2;
 		if (lbn < m->ei_blk)
@@ -59,11 +62,24 @@ static void ext4_ext_binsearch_index(str
 			l = m + 1;
 	}
 
+	if (l == first) {
+		path->ep_sparse_ext.e_blk = *first_lbn;
+		path->ep_sparse_ext.e_len = first->ei_blk - *first_lbn;
+		path->ep_sparse_ext.e_start_hi = 0;
+		path->ep_sparse_ext.e_start_lo = 0;
+		path->ep_is_sparse = 1;
+		return (1);
+	}
 	path->ep_index = l - 1;
+	*first_lbn = path->ep_index->ei_blk;
+	if (path->ep_index < last)
+		*last_lbn = l->ei_blk - 1;
+	return (0);
 }
 
 static void
-ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn)
+ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn,
+		daddr_t first_lbn, daddr_t last_lbn)
 {
 	struct ext4_extent_header *ehp = path->ep_header;
 	struct ext4_extent *first, *l, *r, *m;
@@ -83,8 +99,8 @@ ext4_ext_binsearch(struct inode *ip, str
 	}
 
 	if (l == first) {
-		path->ep_sparse_ext.e_blk = lbn;
-		path->ep_sparse_ext.e_len = first->e_blk - lbn;
+		path->ep_sparse_ext.e_blk = first_lbn;
+		path->ep_sparse_ext.e_len = first->e_blk - first_lbn;
 		path->ep_sparse_ext.e_start_hi = 0;
 		path->ep_sparse_ext.e_start_lo = 0;
 		path->ep_is_sparse = 1;
@@ -92,11 +108,14 @@ ext4_ext_binsearch(struct inode *ip, str
 	}
 	path->ep_ext = l - 1;
 	if (path->ep_ext->e_blk + path->ep_ext->e_len <= lbn) {
-		path->ep_sparse_ext.e_blk = lbn;
+		path->ep_sparse_ext.e_blk = path->ep_ext->e_blk +
+		    path->ep_ext->e_len;
 		if (l <= (first + ehp->eh_ecount - 1))
-			path->ep_sparse_ext.e_len = l->e_blk - lbn;
-		else	// XXX: where does it end?
-			path->ep_sparse_ext.e_len = 1;
+			path->ep_sparse_ext.e_len = l->e_blk -
+			    path->ep_sparse_ext.e_blk;
+		else
+			path->ep_sparse_ext.e_len = last_lbn -
+			    path->ep_sparse_ext.e_blk + 1;
 		path->ep_sparse_ext.e_start_hi = 0;
 		path->ep_sparse_ext.e_start_lo = 0;
 		path->ep_is_sparse = 1;
@@ -162,10 +181,16 @@ ext4_ext_find_extent(struct m_ext2fs *fs
 
 	path->ep_header = ehp;
 
+	daddr_t first_lbn = 0;
+	daddr_t last_lbn = lblkno(ip->i_e2fs, ip->i_size);
+
 	for (i = ehp->eh_depth; i != 0; --i) {
-		ext4_ext_binsearch_index(ip, path, lbn);
-		path->ep_depth = 0;
+		path->ep_depth = i;
 		path->ep_ext = NULL;
+		if (ext4_ext_binsearch_index(ip, path, lbn, &first_lbn,
+		    &last_lbn)) {
+			return (path);
+		}
 
 		nblk = (daddr_t)path->ep_index->ei_leaf_hi << 32 |
 		    path->ep_index->ei_leaf_lo;
@@ -190,6 +215,6 @@ ext4_ext_find_extent(struct m_ext2fs *fs
 	path->ep_index = NULL;
 	path->ep_is_sparse = 0;
 
-	ext4_ext_binsearch(ip, path, lbn);
+	ext4_ext_binsearch(ip, path, lbn, first_lbn, last_lbn);
 	return (path);
 }