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jffs2: implement mount option parsing and compression overriding

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Currently jffs2 has compile-time constants (and .config options)
controlling whether or not the various compression/decompression
drivers are built in and enabled.  This is fine for embedded
systems, but it clashes with distribution kernels.  Distro kernels
tend to turn on everything; this causes OpenFirmware to fall
over, as it understands ZLIB-compressed inodes.  Booting a kernel
that has LZO compression enabled, writing to the boot partition,
and then rebooting causes OFW to fail to read the kernel from
the filesystem.  This is because LZO compression has priority
when writing new data to jffs2, if LZO is enabled.

This patch adds mount option parsing, and a single supported
option ("compr=none").  This adds the flexibility of being
able to specify which compressor overrides on a per-superblock
basis.  For now, we can simply disable compression;
additional flexibility coming soon.

v2: kill some printks, and implement show_options as suggested
by Artem Bityutskiy.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>
This commit is contained in:
Andres Salomon
2011-10-16 18:15:16 -07:00
committed by Artem Bityutskiy
parent 23b1a99b87
commit 92abc475d8
5 changed files with 112 additions and 4 deletions
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9
fs/jffs2/compr.c
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@@ -76,13 +76,18 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
uint32_t *datalen, uint32_t *cdatalen)
{
int ret = JFFS2_COMPR_NONE;
int compr_ret;
int mode, compr_ret;
struct jffs2_compressor *this, *best=NULL;
unsigned char *output_buf = NULL, *tmp_buf;
uint32_t orig_slen, orig_dlen;
uint32_t best_slen=0, best_dlen=0;
switch (jffs2_compression_mode) {
if (c->mount_opts.override_compr)
mode = c->mount_opts.compr;
else
mode = jffs2_compression_mode;
switch (mode) {
case JFFS2_COMPR_MODE_NONE:
break;
case JFFS2_COMPR_MODE_PRIORITY: