Merge git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next
* git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next:
Squashfs: Add an option to set dev block size to 4K
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 048b59d..c70111e 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -78,6 +78,28 @@
If unsure, say N.
+config SQUASHFS_4K_DEVBLK_SIZE
+ bool "Use 4K device block size?"
+ depends on SQUASHFS
+ help
+ By default Squashfs sets the dev block size (sb_min_blocksize)
+ to 1K or the smallest block size supported by the block device
+ (if larger). This, because blocks are packed together and
+ unaligned in Squashfs, should reduce latency.
+
+ This, however, gives poor performance on MTD NAND devices where
+ the optimal I/O size is 4K (even though the devices can support
+ smaller block sizes).
+
+ Using a 4K device block size may also improve overall I/O
+ performance for some file access patterns (e.g. sequential
+ accesses of files in filesystem order) on all media.
+
+ Setting this option will force Squashfs to use a 4K device block
+ size by default.
+
+ If unsure, say N.
+
config SQUASHFS_EMBEDDED
bool "Additional option for memory-constrained systems"
depends on SQUASHFS
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index b4a4e53..e8e1464 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -36,6 +36,13 @@
#define SQUASHFS_FILE_SIZE 131072
#define SQUASHFS_FILE_LOG 17
+/* default size of block device I/O */
+#ifdef CONFIG_SQUASHFS_4K_DEVBLK_SIZE
+#define SQUASHFS_DEVBLK_SIZE 4096
+#else
+#define SQUASHFS_DEVBLK_SIZE 1024
+#endif
+
#define SQUASHFS_FILE_MAX_SIZE 1048576
#define SQUASHFS_FILE_MAX_LOG 20
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 7438850..2da1715 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -95,7 +95,7 @@
}
msblk = sb->s_fs_info;
- msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
+ msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
msblk->devblksize_log2 = ffz(~msblk->devblksize);
mutex_init(&msblk->read_data_mutex);