linux-erofs.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: linux-erofs@lists.ozlabs.org
Cc: nl6720 <nl6720@gmail.com>,
	Lasse Collin <lasse.collin@tukaani.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 1/2] erofs: add support for the full decompressed length
Date: Fri, 13 Aug 2021 13:29:30 +0800	[thread overview]
Message-ID: <20210813052931.203280-2-hsiangkao@linux.alibaba.com> (raw)
In-Reply-To: <20210813052931.203280-1-hsiangkao@linux.alibaba.com>

Previously, there is no need to get the full decompressed length since
EROFS supports partial decompression. However for some other cases
such as fiemap, the full decompressed length is necessary for iomap to
make it work properly.

This patch adds a way to get the full decompressed length. Note that
it takes more metadata overhead and it'd be avoided if possible in the
performance sensitive scenario.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/internal.h |  5 +++
 fs/erofs/zmap.c     | 93 +++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 90 insertions(+), 8 deletions(-)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 25b094085ca6..2a05b09e1c06 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -356,6 +356,11 @@ struct erofs_map_blocks {
 
 /* Flags used by erofs_map_blocks_flatmode() */
 #define EROFS_GET_BLOCKS_RAW    0x0001
+/*
+ * Used to get the exact decompressed length, e.g. fiemap (consider lookback
+ * approach instead if possible since it's quite metadata expensive.)
+ */
+#define EROFS_GET_BLOCKS_FIEMAP	0x0002
 
 /* zmap.c */
 #ifdef CONFIG_EROFS_FS_ZIP
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index f68aea4baed7..12256ef12819 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -212,9 +212,32 @@ static unsigned int decode_compactedbits(unsigned int lobits,
 	return lo;
 }
 
+static int get_compacted_la_distance(unsigned int lclusterbits,
+				     unsigned int encodebits,
+				     unsigned int vcnt, u8 *in, int i)
+{
+	const unsigned int lomask = (1 << lclusterbits) - 1;
+	unsigned int lo, d1 = 0;
+	u8 type;
+
+	for (; i < vcnt; ++i) {
+		lo = decode_compactedbits(lclusterbits, lomask,
+					  in, encodebits * i, &type);
+
+		if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
+			return d1;
+		++d1;
+	}
+
+	/* vcnt - 1 (Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) item */
+	if (!(lo & Z_EROFS_VLE_DI_D0_CBLKCNT))
+		d1 += lo - 1;
+	return d1;
+}
+
 static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 				  unsigned int amortizedshift,
-				  unsigned int eofs)
+				  unsigned int eofs, bool lookahead)
 {
 	struct erofs_inode *const vi = EROFS_I(m->inode);
 	const unsigned int lclusterbits = vi->z_logical_clusterbits;
@@ -243,6 +266,11 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	m->type = type;
 	if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
 		m->clusterofs = 1 << lclusterbits;
+
+		/* figure out lookahead_distance: delta[1] if needed */
+		if (lookahead)
+			m->delta[1] = get_compacted_la_distance(lclusterbits,
+						encodebits, vcnt, in, i);
 		if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
 			if (!big_pcluster) {
 				DBG_BUGON(1);
@@ -313,7 +341,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 }
 
 static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					    unsigned long lcn)
+					    unsigned long lcn, bool lookahead)
 {
 	struct inode *const inode = m->inode;
 	struct erofs_inode *const vi = EROFS_I(inode);
@@ -364,11 +392,12 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 	err = z_erofs_reload_indexes(m, erofs_blknr(pos));
 	if (err)
 		return err;
-	return unpack_compacted_index(m, amortizedshift, erofs_blkoff(pos));
+	return unpack_compacted_index(m, amortizedshift, erofs_blkoff(pos),
+				      lookahead);
 }
 
 static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
-					  unsigned int lcn)
+					  unsigned int lcn, bool lookahead)
 {
 	const unsigned int datamode = EROFS_I(m->inode)->datalayout;
 
@@ -376,7 +405,7 @@ static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 		return legacy_load_cluster_from_disk(m, lcn);
 
 	if (datamode == EROFS_INODE_FLAT_COMPRESSION)
-		return compacted_load_cluster_from_disk(m, lcn);
+		return compacted_load_cluster_from_disk(m, lcn, lookahead);
 
 	return -EINVAL;
 }
@@ -399,7 +428,7 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 
 	/* load extent head logical cluster if needed */
 	lcn -= lookback_distance;
-	err = z_erofs_load_cluster_from_disk(m, lcn);
+	err = z_erofs_load_cluster_from_disk(m, lcn, false);
 	if (err)
 		return err;
 
@@ -450,7 +479,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 	if (m->compressedlcs)
 		goto out;
 
-	err = z_erofs_load_cluster_from_disk(m, lcn);
+	err = z_erofs_load_cluster_from_disk(m, lcn, false);
 	if (err)
 		return err;
 
@@ -498,6 +527,48 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 	return -EFSCORRUPTED;
 }
 
+static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
+{
+	struct inode *inode = m->inode;
+	struct erofs_inode *vi = EROFS_I(inode);
+	struct erofs_map_blocks *map = m->map;
+	unsigned int lclusterbits = vi->z_logical_clusterbits;
+	u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
+	int err;
+
+	do {
+		/* handle the last EOF pcluster (no next HEAD lcluster) */
+		if ((lcn << lclusterbits) >= inode->i_size) {
+			map->m_llen = inode->i_size - map->m_la;
+			return 0;
+		}
+
+		err = z_erofs_load_cluster_from_disk(m, lcn, true);
+		if (err)
+			return err;
+
+		if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
+			if (!m->delta[1])
+				DBG_BUGON(m->clusterofs != 1 << lclusterbits);
+		} else if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
+			   m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD) {
+			/* go on until the next HEAD lcluster */
+			if (lcn != headlcn)
+				break;
+			m->delta[1] = 1;
+		} else {
+			erofs_err(inode->i_sb, "unknown type %u @ lcn %llu of nid %llu",
+				  m->type, lcn, vi->nid);
+			DBG_BUGON(1);
+			return -EOPNOTSUPP;
+		}
+		lcn += m->delta[1];
+	} while (m->delta[1]);
+
+	map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
+	return 0;
+}
+
 int z_erofs_map_blocks_iter(struct inode *inode,
 			    struct erofs_map_blocks *map,
 			    int flags)
@@ -531,7 +602,7 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 	initial_lcn = ofs >> lclusterbits;
 	endoff = ofs & ((1 << lclusterbits) - 1);
 
-	err = z_erofs_load_cluster_from_disk(&m, initial_lcn);
+	err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
 	if (err)
 		goto unmap_out;
 
@@ -581,6 +652,12 @@ int z_erofs_map_blocks_iter(struct inode *inode,
 	err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
 	if (err)
 		goto out;
+
+	if (flags & EROFS_GET_BLOCKS_FIEMAP) {
+		err = z_erofs_get_extent_decompressedlen(&m);
+		if (!err)
+			map->m_flags |= EROFS_MAP_FULL_MAPPED;
+	}
 unmap_out:
 	if (m.kaddr)
 		kunmap_atomic(m.kaddr);
-- 
2.24.4


  reply	other threads:[~2021-08-13  5:29 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-13  5:29 [PATCH 0/2] erofs: add fiemap support with iomap Gao Xiang
2021-08-13  5:29 ` Gao Xiang [this message]
2021-08-14 15:27   ` [PATCH v1.1 1/2] erofs: add support for the full decompressed length Gao Xiang
2021-08-18 14:11     ` Chao Yu
2021-08-18 15:22     ` [PATCH v1.2] " Gao Xiang
2021-08-16 15:38   ` [PATCH 1/2] " Chao Yu
2021-08-17  0:54     ` [PATCH 1/2] erofs: add support for the full decompressed lengthy Gao Xiang
2021-08-13  5:29 ` [PATCH 2/2] erofs: add fiemap support with iomap Gao Xiang
2021-08-18 14:11   ` Chao Yu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210813052931.203280-2-hsiangkao@linux.alibaba.com \
    --to=hsiangkao@linux.alibaba.com \
    --cc=lasse.collin@tukaani.org \
    --cc=linux-erofs@lists.ozlabs.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=nl6720@gmail.com \
    --subject='Re: [PATCH 1/2] erofs: add support for the full decompressed length' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).