f15d9d5123
The 4k-align squashfs patch was broken in the update to squashfs 4.4dev, such that the patch was no longer actually applied in full (command line option not even parsed).
87 lines
3.3 KiB
Diff
87 lines
3.3 KiB
Diff
From 7bda7c75748f36b0a50f93e46144d5a4de4974ad Mon Sep 17 00:00:00 2001
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From: Amin Hassani <ahassani@google.com>
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Date: Thu, 15 Dec 2016 10:43:15 -0800
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Subject: [PATCH] mksquashfs 4K aligns the files inside the squashfs image
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Files inside a squashfs image are not necessarily 4k (4096)
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aligned. This patch starts each file in a 4k aligned address and pads
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zero to the end of the file until it reaches the next 4k aligned
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address. This will not change the size of the compressed
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blocks (especially the last one) and hence it will not change how the
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files are being loaded in kernel or unsquashfs. However on average this
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increases the size of the squashfs image which can be calculated by the
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following formula:
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increased_size = (number_of_unfragmented_files_in_image + number of fragments) * 2048
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The 4k alignment can be enabled by flag '-4k-align'
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---
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diff -u a/squashfs-tools/mksquashfs.c b/squashfs-tools/mksquashfs.c
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--- a/squashfs-tools/mksquashfs.c 2019-07-06 15:50:22.214873176 +0000
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+++ b/squashfs-tools/mksquashfs.c 2019-07-06 15:51:22.244802582 +0000
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@@ -100,7 +100,9 @@
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int use_regex = FALSE;
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int nopad = FALSE;
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int exit_on_error = FALSE;
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+int do_4k_align = FALSE;
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static off_t squashfs_start_offset = 0;
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+#define ALIGN_UP(bytes, size) (bytes = (bytes + size - 1) & ~(size - 1))
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long long global_uid = -1, global_gid = -1;
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@@ -1495,6 +1497,9 @@
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* queue at this time.
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*/
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while(!queue_empty(locked_fragment)) {
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+ // 4k align the start of remaining queued fragments.
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+ if(do_4k_align)
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+ ALIGN_UP(bytes, 4096);
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write_buffer = queue_get(locked_fragment);
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frg = write_buffer->block;
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size = SQUASHFS_COMPRESSED_SIZE_BLOCK(fragment_table[frg].size);
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@@ -2414,6 +2419,9 @@
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compressed_size = SQUASHFS_COMPRESSED_SIZE_BLOCK(c_byte);
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write_buffer->size = compressed_size;
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if(fragments_locked == FALSE) {
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+ // 4k align the start of each fragment.
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+ if(do_4k_align)
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+ ALIGN_UP(bytes, 4096);
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fragment_table[file_buffer->block].size = c_byte;
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fragment_table[file_buffer->block].start_block = bytes;
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write_buffer->block = bytes;
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@@ -2728,6 +2736,10 @@
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long long sparse = 0;
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struct file_buffer *fragment_buffer = NULL;
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+ // 4k align the start of each file.
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+ if(do_4k_align)
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+ ALIGN_UP(bytes, 4096);
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+
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if(pre_duplicate(read_size))
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return write_file_blocks_dup(inode, dir_ent, read_buffer, dup);
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@@ -4808,6 +4820,7 @@
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"compressed", no_fragments ? "no" : noF ? "uncompressed" :
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"compressed", no_xattrs ? "no" : noX ? "uncompressed" :
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"compressed", noI || noId ? "uncompressed" : "compressed");
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+ printf("\t4k %saligned\n", do_4k_align ? "" : "un");
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printf("\tduplicates are %sremoved\n", duplicate_checking ? "" :
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"not ");
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printf("Filesystem size %.2f Kbytes (%.2f Mbytes)\n", bytes / 1024.0,
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@@ -5570,6 +5583,8 @@
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root_name = argv[i];
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} else if(strcmp(argv[i], "-version") == 0) {
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VERSION();
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+ } else if(strcmp(argv[i], "-4k-align") == 0) {
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+ do_4k_align = TRUE;
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} else {
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ERROR("%s: invalid option\n\n", argv[0]);
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printOptions:
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@@ -5613,6 +5628,7 @@
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ERROR("\t\t\tdirectory containing that directory, "
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"rather than the\n");
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ERROR("\t\t\tcontents of the directory\n");
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+ ERROR("-4k-align\t\tenables 4k alignment of all files\n");
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ERROR("\nFilesystem filter options:\n");
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ERROR("-p <pseudo-definition>\tAdd pseudo file "
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"definition\n");
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