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UBIFS: add a superblock flag for free space fix-up 

The 'space_fixup' flag can be set in the superblock of a new filesystem by
mkfs.ubifs to indicate that any eraseblocks with free space remaining should be
fixed-up the first time it's mounted (after which the flag is un-set). This
means that the UBIFS image has been flashed by a "dumb" flasher and the free
space has been actually programmed (writing all 0xFFs), so this free space
cannot be used. UBIFS fixes the free space up by re-writing the contents of all
LEBs with free space using the atomic LEB change UBI operation.

Artem: improved commit message, add some more commentaries to the code.

Signed-off-by: Matthew L. Creech <mlcreech@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Matthew L. Creech 2011-05-05 16:33:20 -04:00 committed by Artem Bityutskiy
parent e11602ea3e
commit 9f58d3503a
4 changed files with 7 additions and 0 deletions
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2
fs/ubifs/debug.c
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@ -316,6 +316,8 @@ void dbg_dump_node(const struct ubifs_info *c, const void *node)
printk(KERN_DEBUG "\tflags %#x\n", sup_flags);
printk(KERN_DEBUG "\t big_lpt %u\n",
!!(sup_flags & UBIFS_FLG_BIGLPT));
printk(KERN_DEBUG "\t space_fixup %u\n",
!!(sup_flags & UBIFS_FLG_SPACE_FIXUP));
printk(KERN_DEBUG "\tmin_io_size %u\n",
le32_to_cpu(sup->min_io_size));
printk(KERN_DEBUG "\tleb_size %u\n",

1
fs/ubifs/sb.c
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@ -617,6 +617,7 @@ int ubifs_read_superblock(struct ubifs_info *c)
c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
memcpy(&c->uuid, &sup->uuid, 16);
c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
/* Automatically increase file system size to the maximum size */
c->old_leb_cnt = c->leb_cnt;

2
fs/ubifs/ubifs-media.h
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@ -408,9 +408,11 @@ enum {
* Superblock flags.
*
* UBIFS_FLG_BIGLPT: if "big" LPT model is used if set
* UBIFS_FLG_SPACE_FIXUP: first-mount "fixup" of free space within LEBs needed
*/
enum {
UBIFS_FLG_BIGLPT = 0x02,
UBIFS_FLG_SPACE_FIXUP = 0x04,
};
/**

2
fs/ubifs/ubifs.h
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@ -1014,6 +1014,7 @@ struct ubifs_debug_info;
* @cmt_wq: wait queue to sleep on if the log is full and a commit is running
*
* @big_lpt: flag that LPT is too big to write whole during commit
* @space_fixup: flag indicating that free space in LEBs needs to be cleaned up
* @no_chk_data_crc: do not check CRCs when reading data nodes (except during
* recovery)
* @bulk_read: enable bulk-reads
@ -1253,6 +1254,7 @@ struct ubifs_info {
wait_queue_head_t cmt_wq;
unsigned int big_lpt:1;
unsigned int space_fixup:1;
unsigned int no_chk_data_crc:1;
unsigned int bulk_read:1;
unsigned int default_compr:2;