Attachment 165366 Details for Bug 205816 – support for EXT4 sparse files, version 3

[patch] support for EXT4 sparse files, version 3

ext4-sparse.txt (text/plain), 5.83 KB, created by Damjan Jovanovic on 2016-01-10 17:20:58 UTC

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Creator: Damjan Jovanovic

Created: 2016-01-10 17:20:58 UTC

Size: 5.83 KB

patch

obsolete

>commit beefde9b4e5fa020e0e365976d29313006ac666c
>Author: Damjan Jovanovic <damjan.jov@gmail.com>
>Date:   Wed Jan 6 19:05:37 2016 +0200
>
>    Implement reading sparse files from EXT4 filesystems.
>
>diff --git a/sys/fs/ext2fs/ext2_bmap.c b/sys/fs/ext2fs/ext2_bmap.c
>index 7d4a880..c2da0b3 100644
>--- a/sys/fs/ext2fs/ext2_bmap.c
>+++ b/sys/fs/ext2fs/ext2_bmap.c
>@@ -102,9 +102,6 @@ ext4_bmapext(struct vnode *vp, int32_t bn, int64_t *bnp, int *runp, int *runb)
> 	fs = ip->i_e2fs;
> 	lbn = bn;
> 
>-	/*
>-	 * TODO: need to implement read ahead to improve the performance.
>-	 */
> 	if (runp != NULL)
> 		*runp = 0;
> 
>@@ -112,15 +109,24 @@ ext4_bmapext(struct vnode *vp, int32_t bn, int64_t *bnp, int *runp, int *runb)
> 		*runb = 0;
> 
> 	ext4_ext_find_extent(fs, ip, lbn, &path);
>-	ep = path.ep_ext;
>-	if (ep == NULL)
>-		ret = EIO;
>-	else {
>-		*bnp = fsbtodb(fs, lbn - ep->e_blk +
>-		    (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32));
>-
>-		if (*bnp == 0)
>-			*bnp = -1;
>+	if (path.ep_is_sparse) {
>+		*bnp = -1;
>+		if (runp != NULL)
>+			*runp = path.ep_sparse_ext.e_len - (lbn - path.ep_sparse_ext.e_blk) - 1;
>+	} else {
>+		ep = path.ep_ext;
>+		if (ep == NULL)
>+			ret = EIO;
>+		else {
>+			*bnp = fsbtodb(fs, lbn - ep->e_blk +
>+			    (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32));
>+
>+			if (*bnp == 0)
>+				*bnp = -1;
>+
>+			if (runp != NULL)
>+				*runp = ep->e_len - (lbn - ep->e_blk) - 1;
>+		}
> 	}
> 
> 	if (path.ep_bp != NULL) {
>diff --git a/sys/fs/ext2fs/ext2_extents.c b/sys/fs/ext2fs/ext2_extents.c
>index 68704bb..0c05d76 100644
>--- a/sys/fs/ext2fs/ext2_extents.c
>+++ b/sys/fs/ext2fs/ext2_extents.c
>@@ -66,13 +66,14 @@ static void
> ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn)
> {
> 	struct ext4_extent_header *ehp = path->ep_header;
>-	struct ext4_extent *l, *r, *m;
>+	struct ext4_extent *first, *l, *r, *m;
> 
> 	if (ehp->eh_ecount == 0)
> 		return;
> 
>-	l = (struct ext4_extent *)(char *)(ehp + 1);
>-	r = (struct ext4_extent *)(char *)(ehp + 1) + ehp->eh_ecount - 1;
>+	first = (struct ext4_extent *)(char *)(ehp + 1);
>+	l = first;
>+	r = first + ehp->eh_ecount - 1;
> 	while (l <= r) {
> 		m = l + (r - l) / 2;
> 		if (lbn < m->e_blk)
>@@ -81,7 +82,25 @@ ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn)
> 			l = m + 1;
> 	}
> 
>+	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_start_hi = 0;
>+		path->ep_sparse_ext.e_start_lo = 0;
>+		path->ep_is_sparse = 1;
>+		return;
>+	}
> 	path->ep_ext = l - 1;
>+	if (path->ep_ext->e_blk + path->ep_ext->e_len <= lbn) {
>+		path->ep_sparse_ext.e_blk = lbn;
>+		if (l <= (first + ehp->eh_ecount - 1))
>+			path->ep_sparse_ext.e_len = l->e_blk - lbn;
>+		else
>+			path->ep_sparse_ext.e_len = 1; // FIXME: where does it end?
>+		path->ep_sparse_ext.e_start_hi = 0;
>+		path->ep_sparse_ext.e_start_lo = 0;
>+		path->ep_is_sparse = 1;
>+	}
> }
> 
> /*
>@@ -169,6 +188,7 @@ ext4_ext_find_extent(struct m_ext2fs *fs, struct inode *ip,
> 	path->ep_depth = i;
> 	path->ep_ext = NULL;
> 	path->ep_index = NULL;
>+	path->ep_is_sparse = 0;
> 
> 	ext4_ext_binsearch(ip, path, lbn);
> 	return (path);
>diff --git a/sys/fs/ext2fs/ext2_extents.h b/sys/fs/ext2fs/ext2_extents.h
>index 94ded83..4ce16f3 100644
>--- a/sys/fs/ext2fs/ext2_extents.h
>+++ b/sys/fs/ext2fs/ext2_extents.h
>@@ -84,7 +84,11 @@ struct ext4_extent_cache {
> struct ext4_extent_path {
> 	uint16_t ep_depth;
> 	struct buf *ep_bp;
>-	struct ext4_extent *ep_ext;
>+	int ep_is_sparse;
>+	union {
>+		struct ext4_extent ep_sparse_ext;
>+		struct ext4_extent *ep_ext;
>+	};
> 	struct ext4_extent_index *ep_index;
> 	struct ext4_extent_header *ep_header;
> };
>diff --git a/sys/fs/ext2fs/ext2_vnops.c b/sys/fs/ext2fs/ext2_vnops.c
>index 5b8990ee..9afb0f9 100644
>--- a/sys/fs/ext2fs/ext2_vnops.c
>+++ b/sys/fs/ext2fs/ext2_vnops.c
>@@ -1787,6 +1787,7 @@ ext2_ioctl(struct vop_ioctl_args *ap)
> static int
> ext4_ext_read(struct vop_read_args *ap)
> {
>+	static unsigned char zeroes[4096];
> 	struct vnode *vp;
> 	struct inode *ip;
> 	struct uio *uio;
>@@ -1831,11 +1832,14 @@ ext4_ext_read(struct vop_read_args *ap)
> 		switch (cache_type) {
> 		case EXT4_EXT_CACHE_NO:
> 			ext4_ext_find_extent(fs, ip, lbn, &path);
>-			ep = path.ep_ext;
>+			if (path.ep_is_sparse)
>+				ep = &path.ep_sparse_ext;
>+			else
>+				ep = path.ep_ext;
> 			if (ep == NULL)
> 				return (EIO);
> 
>-			ext4_ext_put_cache(ip, ep, EXT4_EXT_CACHE_IN);
>+			ext4_ext_put_cache(ip, ep, path.ep_is_sparse ? EXT4_EXT_CACHE_GAP : EXT4_EXT_CACHE_IN);
> 
> 			newblk = lbn - ep->e_blk + (ep->e_start_lo |
> 			    (daddr_t)ep->e_start_hi << 32);
>@@ -1848,7 +1852,7 @@ ext4_ext_read(struct vop_read_args *ap)
> 
> 		case EXT4_EXT_CACHE_GAP:
> 			/* block has not been allocated yet */
>-			return (0);
>+			break;
> 
> 		case EXT4_EXT_CACHE_IN:
> 			newblk = lbn - nex.e_blk + (nex.e_start_lo |
>@@ -1859,24 +1863,32 @@ ext4_ext_read(struct vop_read_args *ap)
> 			panic("%s: invalid cache type", __func__);
> 		}
> 
>-		error = bread(ip->i_devvp, fsbtodb(fs, newblk), size, NOCRED, &bp);
>-		if (error) {
>-			brelse(bp);
>-			return (error);
>-		}
>+		if (cache_type == EXT4_EXT_CACHE_GAP || (cache_type == EXT4_EXT_CACHE_NO && path.ep_is_sparse)) {
>+			if (xfersize > sizeof(zeroes))
>+				xfersize = sizeof(zeroes);
>+			error = uiomove(zeroes, xfersize, uio);
>+			if (error)
>+				return (error);
>+		} else {
>+			error = bread(ip->i_devvp, fsbtodb(fs, newblk), size, NOCRED, &bp);
>+			if (error) {
>+				brelse(bp);
>+				return (error);
>+			}
> 
>-		size -= bp->b_resid;
>-		if (size < xfersize) {
>-			if (size == 0) {
>-				bqrelse(bp);
>-				break;
>+			size -= bp->b_resid;
>+			if (size < xfersize) {
>+				if (size == 0) {
>+					bqrelse(bp);
>+					break;
>+				}
>+				xfersize = size;
> 			}
>-			xfersize = size;
>+			error = uiomove(bp->b_data + blkoffset, (int)xfersize, uio);
>+			bqrelse(bp);
>+			if (error)
>+				return (error);
> 		}
>-		error = uiomove(bp->b_data + blkoffset, (int)xfersize, uio);
>-		bqrelse(bp);
>-		if (error)
>-			return (error);
> 	}
> 
> 	return (0);

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Attachments on bug 205816: 164979 | 165234 | 165366 | 165400 | 165814