1 files changed, 268 insertions, 263 deletions

diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index aa9cd11f4b78..89bc5f825e0a 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -14,6 +14,7 @@
 #include <linux/lzo.h>
 #include <linux/refcount.h>
 #include "compression.h"
+#include "ctree.h"
 
 #define LZO_LEN	4
 
@@ -31,19 +32,19 @@
  *     payload.
  *     One regular LZO compressed extent can have one or more segments.
  *     For inlined LZO compressed extent, only one segment is allowed.
- *     One segment represents at most one page of uncompressed data.
+ *     One segment represents at most one sector of uncompressed data.
  *
  * 2.1 Segment header
  *     Fixed size. LZO_LEN (4) bytes long, LE32.
  *     Records the total size of the segment (not including the header).
- *     Segment header never crosses page boundary, thus it's possible to
- *     have at most 3 padding zeros at the end of the page.
+ *     Segment header never crosses sector boundary, thus it's possible to
+ *     have at most 3 padding zeros at the end of the sector.
  *
  * 2.2 Data Payload
- *     Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
- *     which is 4419 for a 4KiB page.
+ *     Variable size. Size up limit should be lzo1x_worst_compress(sectorsize)
+ *     which is 4419 for a 4KiB sectorsize.
  *
- * Example:
+ * Example with 4K sectorsize:
  * Page 1:
  *          0     0x2   0x4   0x6   0x8   0xa   0xc   0xe     0x10
  * 0x0000   |  Header   | SegHdr 01 | Data payload 01 ...     |
@@ -54,6 +55,9 @@
  * 0x1000   | SegHdr N+1| Data payload N+1 ...                |
  */
 
+#define WORKSPACE_BUF_LENGTH	(lzo1x_worst_compress(PAGE_SIZE))
+#define WORKSPACE_CBUF_LENGTH	(lzo1x_worst_compress(PAGE_SIZE))
+
 struct workspace {
 	void *mem;
 	void *buf;	/* where decompressed data goes */
@@ -82,8 +86,8 @@ struct list_head *lzo_alloc_workspace(unsigned int level)
 		return ERR_PTR(-ENOMEM);
 
 	workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
-	workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
-	workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
+	workspace->buf = kvmalloc(WORKSPACE_BUF_LENGTH, GFP_KERNEL);
+	workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, GFP_KERNEL);
 	if (!workspace->mem || !workspace->buf || !workspace->cbuf)
 		goto fail;
 
@@ -111,312 +115,313 @@ static inline size_t read_compress_length(const char *buf)
 	return le32_to_cpu(dlen);
 }
 
+/*
+ * Will do:
+ *
+ * - Write a segment header into the destination
+ * - Copy the compressed buffer into the destination
+ * - Make sure we have enough space in the last sector to fit a segment header
+ *   If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros.
+ *
+ * Will allocate new pages when needed.
+ */
+static int copy_compressed_data_to_page(char *compressed_data,
+					size_t compressed_size,
+					struct page **out_pages,
+					unsigned long max_nr_page,
+					u32 *cur_out,
+					const u32 sectorsize)
+{
+	u32 sector_bytes_left;
+	u32 orig_out;
+	struct page *cur_page;
+	char *kaddr;
+
+	if ((*cur_out / PAGE_SIZE) >= max_nr_page)
+		return -E2BIG;
+
+	/*
+	 * We never allow a segment header crossing sector boundary, previous
+	 * run should ensure we have enough space left inside the sector.
+	 */
+	ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize);
+
+	cur_page = out_pages[*cur_out / PAGE_SIZE];
+	/* Allocate a new page */
+	if (!cur_page) {
+		cur_page = alloc_page(GFP_NOFS);
+		if (!cur_page)
+			return -ENOMEM;
+		out_pages[*cur_out / PAGE_SIZE] = cur_page;
+	}
+
+	kaddr = kmap_local_page(cur_page);
+	write_compress_length(kaddr + offset_in_page(*cur_out),
+			      compressed_size);
+	*cur_out += LZO_LEN;
+
+	orig_out = *cur_out;
+
+	/* Copy compressed data */
+	while (*cur_out - orig_out < compressed_size) {
+		u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,
+				     orig_out + compressed_size - *cur_out);
+
+		kunmap_local(kaddr);
+
+		if ((*cur_out / PAGE_SIZE) >= max_nr_page)
+			return -E2BIG;
+
+		cur_page = out_pages[*cur_out / PAGE_SIZE];
+		/* Allocate a new page */
+		if (!cur_page) {
+			cur_page = alloc_page(GFP_NOFS);
+			if (!cur_page)
+				return -ENOMEM;
+			out_pages[*cur_out / PAGE_SIZE] = cur_page;
+		}
+		kaddr = kmap_local_page(cur_page);
+
+		memcpy(kaddr + offset_in_page(*cur_out),
+		       compressed_data + *cur_out - orig_out, copy_len);
+
+		*cur_out += copy_len;
+	}
+
+	/*
+	 * Check if we can fit the next segment header into the remaining space
+	 * of the sector.
+	 */
+	sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
+	if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0)
+		goto out;
+
+	/* The remaining size is not enough, pad it with zeros */
+	memset(kaddr + offset_in_page(*cur_out), 0,
+	       sector_bytes_left);
+	*cur_out += sector_bytes_left;
+
+out:
+	kunmap_local(kaddr);
+	return 0;
+}
+
 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
 		u64 start, struct page **pages, unsigned long *out_pages,
 		unsigned long *total_in, unsigned long *total_out)
 {
 	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize;
+	struct page *page_in = NULL;
+	char *sizes_ptr;
+	const unsigned long max_nr_page = *out_pages;
 	int ret = 0;
-	char *data_in;
-	char *cpage_out;
-	int nr_pages = 0;
-	struct page *in_page = NULL;
-	struct page *out_page = NULL;
-	unsigned long bytes_left;
-	unsigned long len = *total_out;
-	unsigned long nr_dest_pages = *out_pages;
-	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
-	size_t in_len;
-	size_t out_len;
-	char *buf;
-	unsigned long tot_in = 0;
-	unsigned long tot_out = 0;
-	unsigned long pg_bytes_left;
-	unsigned long out_offset;
-	unsigned long bytes;
+	/* Points to the file offset of input data */
+	u64 cur_in = start;
+	/* Points to the current output byte */
+	u32 cur_out = 0;
+	u32 len = *total_out;
 
+	ASSERT(max_nr_page > 0);
 	*out_pages = 0;
 	*total_out = 0;
 	*total_in = 0;
 
-	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-	data_in = kmap(in_page);
-
 	/*
-	 * store the size of all chunks of compressed data in
-	 * the first 4 bytes
+	 * Skip the header for now, we will later come back and write the total
+	 * compressed size
 	 */
-	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
-	if (out_page == NULL) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	cpage_out = kmap(out_page);
-	out_offset = LZO_LEN;
-	tot_out = LZO_LEN;
-	pages[0] = out_page;
-	nr_pages = 1;
-	pg_bytes_left = PAGE_SIZE - LZO_LEN;
-
-	/* compress at most one page of data each time */
-	in_len = min(len, PAGE_SIZE);
-	while (tot_in < len) {
-		ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
-				       &out_len, workspace->mem);
-		if (ret != LZO_E_OK) {
-			pr_debug("BTRFS: lzo in loop returned %d\n",
-			       ret);
+	cur_out += LZO_LEN;
+	while (cur_in < start + len) {
+		char *data_in;
+		const u32 sectorsize_mask = sectorsize - 1;
+		u32 sector_off = (cur_in - start) & sectorsize_mask;
+		u32 in_len;
+		size_t out_len;
+
+		/* Get the input page first */
+		if (!page_in) {
+			page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT);
+			ASSERT(page_in);
+		}
+
+		/* Compress at most one sector of data each time */
+		in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
+		ASSERT(in_len);
+		data_in = kmap_local_page(page_in);
+		ret = lzo1x_1_compress(data_in +
+				       offset_in_page(cur_in), in_len,
+				       workspace->cbuf, &out_len,
+				       workspace->mem);
+		kunmap_local(data_in);
+		if (ret < 0) {
+			pr_debug("BTRFS: lzo in loop returned %d\n", ret);
 			ret = -EIO;
 			goto out;
 		}
 
-		/* store the size of this chunk of compressed data */
-		write_compress_length(cpage_out + out_offset, out_len);
-		tot_out += LZO_LEN;
-		out_offset += LZO_LEN;
-		pg_bytes_left -= LZO_LEN;
-
-		tot_in += in_len;
-		tot_out += out_len;
-
-		/* copy bytes from the working buffer into the pages */
-		buf = workspace->cbuf;
-		while (out_len) {
-			bytes = min_t(unsigned long, pg_bytes_left, out_len);
-
-			memcpy(cpage_out + out_offset, buf, bytes);
-
-			out_len -= bytes;
-			pg_bytes_left -= bytes;
-			buf += bytes;
-			out_offset += bytes;
+		ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
+						   pages, max_nr_page,
+						   &cur_out, sectorsize);
+		if (ret < 0)
+			goto out;
 
-			/*
-			 * we need another page for writing out.
-			 *
-			 * Note if there's less than 4 bytes left, we just
-			 * skip to a new page.
-			 */
-			if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
-			    pg_bytes_left == 0) {
-				if (pg_bytes_left) {
-					memset(cpage_out + out_offset, 0,
-					       pg_bytes_left);
-					tot_out += pg_bytes_left;
-				}
-
-				/* we're done, don't allocate new page */
-				if (out_len == 0 && tot_in >= len)
-					break;
-
-				kunmap(out_page);
-				if (nr_pages == nr_dest_pages) {
-					out_page = NULL;
-					ret = -E2BIG;
-					goto out;
-				}
-
-				out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
-				if (out_page == NULL) {
-					ret = -ENOMEM;
-					goto out;
-				}
-				cpage_out = kmap(out_page);
-				pages[nr_pages++] = out_page;
-
-				pg_bytes_left = PAGE_SIZE;
-				out_offset = 0;
-			}
-		}
+		cur_in += in_len;
 
-		/* we're making it bigger, give up */
-		if (tot_in > 8192 && tot_in < tot_out) {
+		/*
+		 * Check if we're making it bigger after two sectors.  And if
+		 * it is so, give up.
+		 */
+		if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) {
 			ret = -E2BIG;
 			goto out;
 		}
 
-		/* we're all done */
-		if (tot_in >= len)
-			break;
-
-		if (tot_out > max_out)
-			break;
+		/* Check if we have reached page boundary */
+		if (IS_ALIGNED(cur_in, PAGE_SIZE)) {
+			put_page(page_in);
+			page_in = NULL;
+		}
+	}
 
-		bytes_left = len - tot_in;
-		kunmap(in_page);
-		put_page(in_page);
+	/* Store the size of all chunks of compressed data */
+	sizes_ptr = kmap_local_page(pages[0]);
+	write_compress_length(sizes_ptr, cur_out);
+	kunmap_local(sizes_ptr);
 
-		start += PAGE_SIZE;
-		in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-		data_in = kmap(in_page);
-		in_len = min(bytes_left, PAGE_SIZE);
-	}
+	ret = 0;
+	*total_out = cur_out;
+	*total_in = cur_in - start;
+out:
+	if (page_in)
+		put_page(page_in);
+	*out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE);
+	return ret;
+}
 
-	if (tot_out >= tot_in) {
-		ret = -E2BIG;
-		goto out;
-	}
+/*
+ * Copy the compressed segment payload into @dest.
+ *
+ * For the payload there will be no padding, just need to do page switching.
+ */
+static void copy_compressed_segment(struct compressed_bio *cb,
+				    char *dest, u32 len, u32 *cur_in)
+{
+	u32 orig_in = *cur_in;
 
-	/* store the size of all chunks of compressed data */
-	cpage_out = kmap(pages[0]);
-	write_compress_length(cpage_out, tot_out);
+	while (*cur_in < orig_in + len) {
+		struct page *cur_page;
+		u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
+					  orig_in + len - *cur_in);
 
-	kunmap(pages[0]);
+		ASSERT(copy_len);
+		cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];
 
-	ret = 0;
-	*total_out = tot_out;
-	*total_in = tot_in;
-out:
-	*out_pages = nr_pages;
-	if (out_page)
-		kunmap(out_page);
+		memcpy_from_page(dest + *cur_in - orig_in, cur_page,
+				 offset_in_page(*cur_in), copy_len);
 
-	if (in_page) {
-		kunmap(in_page);
-		put_page(in_page);
+		*cur_in += copy_len;
 	}
-
-	return ret;
 }
 
 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 {
 	struct workspace *workspace = list_entry(ws, struct workspace, list);
-	int ret = 0, ret2;
-	char *data_in;
-	unsigned long page_in_index = 0;
-	size_t srclen = cb->compressed_len;
-	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
-	unsigned long buf_start;
-	unsigned long buf_offset = 0;
-	unsigned long bytes;
-	unsigned long working_bytes;
-	size_t in_len;
-	size_t out_len;
-	const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
-	unsigned long in_offset;
-	unsigned long in_page_bytes_left;
-	unsigned long tot_in;
-	unsigned long tot_out;
-	unsigned long tot_len;
-	char *buf;
-	bool may_late_unmap, need_unmap;
-	struct page **pages_in = cb->compressed_pages;
-	u64 disk_start = cb->start;
-	struct bio *orig_bio = cb->orig_bio;
-
-	data_in = kmap(pages_in[0]);
-	tot_len = read_compress_length(data_in);
+	const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
+	const u32 sectorsize = fs_info->sectorsize;
+	char *kaddr;
+	int ret;
+	/* Compressed data length, can be unaligned */
+	u32 len_in;
+	/* Offset inside the compressed data */
+	u32 cur_in = 0;
+	/* Bytes decompressed so far */
+	u32 cur_out = 0;
+
+	kaddr = kmap_local_page(cb->compressed_pages[0]);
+	len_in = read_compress_length(kaddr);
+	kunmap_local(kaddr);
+	cur_in += LZO_LEN;
+
 	/*
-	 * Compressed data header check.
+	 * LZO header length check
 	 *
-	 * The real compressed size can't exceed the maximum extent length, and
-	 * all pages should be used (whole unused page with just the segment
-	 * header is not possible).  If this happens it means the compressed
-	 * extent is corrupted.
+	 * The total length should not exceed the maximum extent length,
+	 * and all sectors should be used.
+	 * If this happens, it means the compressed extent is corrupted.
 	 */
-	if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
-	    tot_len < srclen - PAGE_SIZE) {
-		ret = -EUCLEAN;
-		goto done;
+	if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
+	    round_up(len_in, sectorsize) < cb->compressed_len) {
+		btrfs_err(fs_info,
+			"invalid lzo header, lzo len %u compressed len %u",
+			len_in, cb->compressed_len);
+		return -EUCLEAN;
 	}
 
-	tot_in = LZO_LEN;
-	in_offset = LZO_LEN;
-	in_page_bytes_left = PAGE_SIZE - LZO_LEN;
-
-	tot_out = 0;
-
-	while (tot_in < tot_len) {
-		in_len = read_compress_length(data_in + in_offset);
-		in_page_bytes_left -= LZO_LEN;
-		in_offset += LZO_LEN;
-		tot_in += LZO_LEN;
+	/* Go through each lzo segment */
+	while (cur_in < len_in) {
+		struct page *cur_page;
+		/* Length of the compressed segment */
+		u32 seg_len;
+		u32 sector_bytes_left;
+		size_t out_len = lzo1x_worst_compress(sectorsize);
 
 		/*
-		 * Segment header check.
-		 *
-		 * The segment length must not exceed the maximum LZO
-		 * compression size, nor the total compressed size.
+		 * We should always have enough space for one segment header
+		 * inside current sector.
 		 */
-		if (in_len > max_segment_len || tot_in + in_len > tot_len) {
-			ret = -EUCLEAN;
-			goto done;
-		}
-
-		tot_in += in_len;
-		working_bytes = in_len;
-		may_late_unmap = need_unmap = false;
-
-		/* fast path: avoid using the working buffer */
-		if (in_page_bytes_left >= in_len) {
-			buf = data_in + in_offset;
-			bytes = in_len;
-			may_late_unmap = true;
-			goto cont;
+		ASSERT(cur_in / sectorsize ==
+		       (cur_in + LZO_LEN - 1) / sectorsize);
+		cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];
+		ASSERT(cur_page);
+		kaddr = kmap_local_page(cur_page);
+		seg_len = read_compress_length(kaddr + offset_in_page(cur_in));
+		kunmap_local(kaddr);
+		cur_in += LZO_LEN;
+
+		if (seg_len > WORKSPACE_CBUF_LENGTH) {
+			/*
+			 * seg_len shouldn't be larger than we have allocated
+			 * for workspace->cbuf
+			 */
+			btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
+					seg_len);
+			ret = -EIO;
+			goto out;
 		}
 
-		/* copy bytes from the pages into the working buffer */
-		buf = workspace->cbuf;
-		buf_offset = 0;
-		while (working_bytes) {
-			bytes = min(working_bytes, in_page_bytes_left);
-
-			memcpy(buf + buf_offset, data_in + in_offset, bytes);
-			buf_offset += bytes;
-cont:
-			working_bytes -= bytes;
-			in_page_bytes_left -= bytes;
-			in_offset += bytes;
-
-			/* check if we need to pick another page */
-			if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
-			    || in_page_bytes_left == 0) {
-				tot_in += in_page_bytes_left;
-
-				if (working_bytes == 0 && tot_in >= tot_len)
-					break;
-
-				if (page_in_index + 1 >= total_pages_in) {
-					ret = -EIO;
-					goto done;
-				}
-
-				if (may_late_unmap)
-					need_unmap = true;
-				else
-					kunmap(pages_in[page_in_index]);
-
-				data_in = kmap(pages_in[++page_in_index]);
-
-				in_page_bytes_left = PAGE_SIZE;
-				in_offset = 0;
-			}
-		}
+		/* Copy the compressed segment payload into workspace */
+		copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
 
-		out_len = max_segment_len;
-		ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
-					    &out_len);
-		if (need_unmap)
-			kunmap(pages_in[page_in_index - 1]);
+		/* Decompress the data */
+		ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
+					    workspace->buf, &out_len);
 		if (ret != LZO_E_OK) {
-			pr_warn("BTRFS: decompress failed\n");
+			btrfs_err(fs_info, "failed to decompress");
 			ret = -EIO;
-			break;
+			goto out;
 		}
 
-		buf_start = tot_out;
-		tot_out += out_len;
+		/* Copy the data into inode pages */
+		ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
+		cur_out += out_len;
+
+		/* All data read, exit */
+		if (ret == 0)
+			goto out;
+		ret = 0;
 
-		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
-						 tot_out, disk_start, orig_bio);
-		if (ret2 == 0)
-			break;
+		/* Check if the sector has enough space for a segment header */
+		sector_bytes_left = sectorsize - (cur_in % sectorsize);
+		if (sector_bytes_left >= LZO_LEN)
+			continue;
+
+		/* Skip the padding zeros */
+		cur_in += sector_bytes_left;
 	}
-done:
-	kunmap(pages_in[page_in_index]);
+out:
 	if (!ret)
-		zero_fill_bio(orig_bio);
+		zero_fill_bio(cb->orig_bio);
 	return ret;
 }
 
@@ -427,7 +432,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 	struct workspace *workspace = list_entry(ws, struct workspace, list);
 	size_t in_len;
 	size_t out_len;
-	size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
+	size_t max_segment_len = WORKSPACE_BUF_LENGTH;
 	int ret = 0;
 	char *kaddr;
 	unsigned long bytes;
@@ -467,7 +472,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 	bytes = min_t(unsigned long, destlen, out_len - start_byte);
 
-	kaddr = kmap_atomic(dest_page);
+	kaddr = kmap_local_page(dest_page);
 	memcpy(kaddr, workspace->buf + start_byte, bytes);
 
 	/*
@@ -477,7 +482,7 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 	 */
 	if (bytes < destlen)
 		memset(kaddr+bytes, 0, destlen-bytes);
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 out:
 	return ret;
 }