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	When logical address of a regular extent is 0, the extent is sparse and consists of all zeros. Without this when sparse extents are used in a file reading fails with Cannot map logical address 0 to physical Signed-off-by: Marek Behún <marek.behun@nic.cz>
		
			
				
	
	
		
			127 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			127 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
// SPDX-License-Identifier: GPL-2.0+
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/*
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 * BTRFS filesystem implementation for U-Boot
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 *
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 * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
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 */
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#include "btrfs.h"
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#include <malloc.h>
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#include <memalign.h>
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u64 btrfs_read_extent_inline(struct btrfs_path *path,
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			     struct btrfs_file_extent_item *extent, u64 offset,
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			     u64 size, char *out)
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{
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	u32 clen, dlen, orig_size = size, res;
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	const char *cbuf;
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	char *dbuf;
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	const int data_off = offsetof(struct btrfs_file_extent_item,
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				      disk_bytenr);
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	clen = btrfs_path_item_size(path) - data_off;
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	cbuf = (const char *) extent + data_off;
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	dlen = extent->ram_bytes;
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	if (offset > dlen)
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		return -1ULL;
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	if (size > dlen - offset)
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		size = dlen - offset;
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	if (extent->compression == BTRFS_COMPRESS_NONE) {
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		memcpy(out, cbuf + offset, size);
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		return size;
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	}
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	if (dlen > orig_size) {
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		dbuf = malloc(dlen);
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		if (!dbuf)
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			return -1ULL;
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	} else {
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		dbuf = out;
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	}
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	res = btrfs_decompress(extent->compression, cbuf, clen, dbuf, dlen);
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	if (res == -1 || res != dlen)
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		goto err;
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	if (dlen > orig_size) {
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		memcpy(out, dbuf + offset, size);
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		free(dbuf);
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	} else if (offset) {
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		memmove(out, dbuf + offset, size);
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	}
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	return size;
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err:
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	if (dlen > orig_size)
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		free(dbuf);
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	return -1ULL;
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}
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u64 btrfs_read_extent_reg(struct btrfs_path *path,
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			  struct btrfs_file_extent_item *extent, u64 offset,
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			  u64 size, char *out)
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{
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	u64 physical, clen, dlen, orig_size = size;
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	u32 res;
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	char *cbuf, *dbuf;
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	clen = extent->disk_num_bytes;
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	dlen = extent->num_bytes;
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	if (offset > dlen)
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		return -1ULL;
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	if (size > dlen - offset)
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		size = dlen - offset;
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	/* sparse extent */
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	if (extent->disk_bytenr == 0) {
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		memset(out, 0, size);
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		return size;
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	}
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	physical = btrfs_map_logical_to_physical(extent->disk_bytenr);
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	if (physical == -1ULL)
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		return -1ULL;
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	if (extent->compression == BTRFS_COMPRESS_NONE) {
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		physical += extent->offset + offset;
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		if (!btrfs_devread(physical, size, out))
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			return -1ULL;
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		return size;
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	}
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	cbuf = malloc_cache_aligned(dlen > size ? clen + dlen : clen);
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	if (!cbuf)
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		return -1ULL;
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	if (dlen > orig_size)
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		dbuf = cbuf + clen;
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	else
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		dbuf = out;
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	if (!btrfs_devread(physical, clen, cbuf))
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		goto err;
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	res = btrfs_decompress(extent->compression, cbuf, clen, dbuf, dlen);
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	if (res == -1)
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		goto err;
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	if (dlen > orig_size)
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		memcpy(out, dbuf + offset, size);
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	else
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		memmove(out, dbuf + offset, size);
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	free(cbuf);
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	return res;
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err:
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	free(cbuf);
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	return -1ULL;
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}
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