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ext4_journal: add comments to the code part 2.

pull/11/head
ngkaho1234 9 years ago
parent
b465297573
commit
3cf7bf8bd1
1 changed files with 106 additions and 2 deletions
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  1. 108
      lwext4/ext4_journal.c

108
lwext4/ext4_journal.c
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@ -587,6 +587,9 @@ jbd_revoke_entry_lookup(struct recover_info *info, ext4_fsblk_t block)
return RB_FIND(jbd_revoke, &info->revoke_root, &tmp);
}
/**@brief Replay a block in a transaction.
* @param jbd_fs jbd filesystem
* @param block block address to be replayed.*/
static void jbd_replay_block_tags(struct jbd_fs *jbd_fs,
ext4_fsblk_t block,
uint8_t *uuid __unused,
@ -602,6 +605,8 @@ static void jbd_replay_block_tags(struct jbd_fs *jbd_fs,
(*this_block)++;
/* We replay this block only if the current transaction id
* is equal or greater than that in revoke entry.*/
revoke_entry = jbd_revoke_entry_lookup(info, block);
if (revoke_entry &&
arg->this_trans_id < revoke_entry->trans_id)
@ -615,6 +620,7 @@ static void jbd_replay_block_tags(struct jbd_fs *jbd_fs,
if (r != EOK)
return;
/* We need special treatment for ext4 superblock. */
if (block) {
r = ext4_block_get_noread(fs->bdev, &ext4_block, block);
if (r != EOK) {
@ -652,12 +658,18 @@ static void jbd_replay_block_tags(struct jbd_fs *jbd_fs,
return;
}
/**@brief Add block address to revoke tree, along with
* its transaction id.
* @param info journal replay info
* @param block block address to be replayed.*/
static void jbd_add_revoke_block_tags(struct recover_info *info,
ext4_fsblk_t block)
{
struct revoke_entry *revoke_entry;
ext4_dbg(DEBUG_JBD, "Add block %" PRIu64 " to revoke tree\n", block);
/* If the revoke entry with respect to the block address
* exists already, update its transaction id.*/
revoke_entry = jbd_revoke_entry_lookup(info, block);
if (revoke_entry) {
revoke_entry->trans_id = info->this_trans_id;
@ -695,7 +707,10 @@ do { \
#define ACTION_REVOKE 1
#define ACTION_RECOVER 2
/**@brief Add entries in a revoke block to revoke tree.
* @param jbd_fs jbd filesystem
* @param header revoke block header
* @param recover_info journal replay info*/
static void jbd_build_revoke_tree(struct jbd_fs *jbd_fs,
struct jbd_bhdr *header,
struct recover_info *info)
@ -704,6 +719,8 @@ static void jbd_build_revoke_tree(struct jbd_fs *jbd_fs,
struct jbd_revoke_header *revoke_hdr =
(struct jbd_revoke_header *)header;
uint32_t i, nr_entries, record_len = 4;
/* If we are working on a 64bit jbd filesystem, */
if (JBD_HAS_INCOMPAT_FEATURE(&jbd_fs->sb,
JBD_FEATURE_INCOMPAT_64BIT))
record_len = 8;
@ -752,6 +769,11 @@ static void jbd_replay_descriptor_block(struct jbd_fs *jbd_fs,
arg);
}
/**@brief The core routine of journal replay.
* @param jbd_fs jbd filesystem
* @param recover_info journal replay info
* @param action action needed to be taken
* @return standard error code*/
int jbd_iterate_log(struct jbd_fs *jbd_fs,
struct recover_info *info,
int action)
@ -762,6 +784,7 @@ int jbd_iterate_log(struct jbd_fs *jbd_fs,
uint32_t start_trans_id, this_trans_id;
uint32_t start_block, this_block;
/* We start iterating valid blocks in the whole journal.*/
start_trans_id = this_trans_id = jbd_get32(sb, sequence);
start_block = this_block = jbd_get32(sb, start);
@ -771,6 +794,10 @@ int jbd_iterate_log(struct jbd_fs *jbd_fs,
while (!log_end) {
struct ext4_block block;
struct jbd_bhdr *header;
/* If we are not scanning for the last
* valid transaction in the journal,
* we will stop when we reach the end of
* the journal.*/
if (action != ACTION_SCAN)
if (this_trans_id > info->last_trans_id) {
log_end = true;
@ -782,12 +809,19 @@ int jbd_iterate_log(struct jbd_fs *jbd_fs,
break;
header = (struct jbd_bhdr *)block.data;
/* This block does not have a valid magic number,
* so we have reached the end of the journal.*/
if (jbd_get32(header, magic) != JBD_MAGIC_NUMBER) {
jbd_block_set(jbd_fs, &block);
log_end = true;
continue;
}
/* If the transaction id we found is not expected,
* we may have reached the end of the journal.
*
* If we are not scanning the journal, something
* bad might have taken place. :-( */
if (jbd_get32(header, sequence) != this_trans_id) {
if (action != ACTION_SCAN)
r = EIO;
@ -819,6 +853,9 @@ int jbd_iterate_log(struct jbd_fs *jbd_fs,
ext4_dbg(DEBUG_JBD, "Commit block: %" PRIu32", "
"trans_id: %" PRIu32"\n",
this_block, this_trans_id);
/* This is the end of a transaction,
* we may now proceed to the next transaction.
*/
this_trans_id++;
break;
case JBD_REVOKE_BLOCK:
@ -844,6 +881,7 @@ int jbd_iterate_log(struct jbd_fs *jbd_fs,
}
ext4_dbg(DEBUG_JBD, "End of journal.\n");
if (r == EOK && action == ACTION_SCAN) {
/* We have finished scanning the journal. */
info->start_trans_id = start_trans_id;
if (this_trans_id > start_trans_id)
info->last_trans_id = this_trans_id - 1;
@ -854,6 +892,9 @@ int jbd_iterate_log(struct jbd_fs *jbd_fs,
return r;
}
/**@brief Replay journal.
* @param jbd_fs jbd filesystem
* @return standard error code*/
int jbd_recover(struct jbd_fs *jbd_fs)
{
int r;
@ -874,6 +915,10 @@ int jbd_recover(struct jbd_fs *jbd_fs)
r = jbd_iterate_log(jbd_fs, &info, ACTION_RECOVER);
if (r == EOK) {
/* If we successfully replay the journal,
* clear EXT4_FINCOM_RECOVER flag on the
* ext4 superblock, and set the start of
* journal to 0.*/
uint32_t features_incompatible =
ext4_get32(&jbd_fs->inode_ref.fs->sb,
features_incompatible);
@ -898,6 +943,10 @@ void jbd_journal_write_sb(struct jbd_journal *journal)
jbd_fs->dirty = true;
}
/**@brief Start accessing the journal.
* @param jbd_fs jbd filesystem
* @param journal current journal session
* @return standard error code*/
int jbd_journal_start(struct jbd_fs *jbd_fs,
struct jbd_journal *journal)
{
@ -929,14 +978,19 @@ int jbd_journal_start(struct jbd_fs *jbd_fs,
return jbd_write_sb(jbd_fs);
}
/**@brief Stop accessing the journal.
* @param journal current journal session
* @return standard error code*/
int jbd_journal_stop(struct jbd_journal *journal)
{
int r;
struct jbd_fs *jbd_fs = journal->jbd_fs;
uint32_t features_incompatible;
/* Commit all the transactions to the journal.*/
jbd_journal_commit_all(journal);
/* Make sure that journalled content have reached
* the disk.*/
ext4_block_cache_flush(jbd_fs->inode_ref.fs->bdev);
features_incompatible =
@ -957,6 +1011,10 @@ int jbd_journal_stop(struct jbd_journal *journal)
return jbd_write_sb(journal->jbd_fs);
}
/**@brief Allocate a block in the journal.
* @param journal current journal session
* @param trans transaction
* @return allocated block address*/
static uint32_t jbd_journal_alloc_block(struct jbd_journal *journal,
struct jbd_trans *trans)
{
@ -965,12 +1023,18 @@ static uint32_t jbd_journal_alloc_block(struct jbd_journal *journal,
start_block = journal->last++;
trans->alloc_blocks++;
wrap(&journal->jbd_fs->sb, journal->last);
/* If there is no space left, flush all journalled
* blocks to disk first.*/
if (journal->last == journal->start)
ext4_block_cache_flush(journal->jbd_fs->inode_ref.fs->bdev);
return start_block;
}
/**@brief Allocate a new transaction
* @param journal current journal session
* @return transaction allocated*/
struct jbd_trans *
jbd_journal_new_trans(struct jbd_journal *journal)
{
@ -990,6 +1054,10 @@ static void jbd_trans_end_write(struct ext4_bcache *bc __unused,
int res,
void *arg);
/**@brief Add block to a transaction
* @param trans transaction
* @param block block descriptor
* @return standard error code*/
int jbd_trans_add_block(struct jbd_trans *trans,
struct ext4_block *block)
{
@ -1007,6 +1075,8 @@ int jbd_trans_add_block(struct jbd_trans *trans,
buf->block = *block;
ext4_bcache_inc_ref(block->buf);
/* If the content reach the disk, notify us
* so that we may do a checkpoint. */
block->buf->end_write = jbd_trans_end_write;
block->buf->end_write_arg = trans;
@ -1015,6 +1085,10 @@ int jbd_trans_add_block(struct jbd_trans *trans,
return EOK;
}
/**@brief Add block to be revoked to a transaction
* @param trans transaction
* @param lba logical block address
* @return standard error code*/
int jbd_trans_revoke_block(struct jbd_trans *trans,
ext4_fsblk_t lba)
{
@ -1028,6 +1102,11 @@ int jbd_trans_revoke_block(struct jbd_trans *trans,
return EOK;
}
/**@brief Free a transaction
* @param journal current journal session
* @param trans transaction
* @param abort discard all the modifications on the block?
* @return standard error code*/
void jbd_journal_free_trans(struct jbd_journal *journal,
struct jbd_trans *trans,
bool abort)
@ -1052,6 +1131,9 @@ void jbd_journal_free_trans(struct jbd_journal *journal,
free(trans);
}
/**@brief Write commit block for a transaction
* @param trans transaction
* @return standard error code*/
static int jbd_trans_write_commit_block(struct jbd_trans *trans)
{
int rc;
@ -1079,6 +1161,10 @@ static int jbd_trans_write_commit_block(struct jbd_trans *trans)
return EOK;
}
/**@brief Write descriptor block for a transaction
* @param journal current journal session
* @param trans transaction
* @return standard error code*/
static int jbd_journal_prepare(struct jbd_journal *journal,
struct jbd_trans *trans)
{
@ -1164,6 +1250,10 @@ again:
return rc;
}
/**@brief Write revoke block for a transaction
* @param journal current journal session
* @param trans transaction
* @return standard error code*/
static int
jbd_journal_prepare_revoke(struct jbd_journal *journal,
struct jbd_trans *trans)
@ -1243,6 +1333,9 @@ again:
return rc;
}
/**@brief Submit the transaction to transaction queue.
* @param journal current journal session
* @param trans transaction*/
void
jbd_journal_submit_trans(struct jbd_journal *journal,
struct jbd_trans *trans)
@ -1252,6 +1345,9 @@ jbd_journal_submit_trans(struct jbd_journal *journal,
trans_node);
}
/**@brief Put references of block descriptors in a transaction.
* @param journal current journal session
* @param trans transaction*/
void jbd_journal_cp_trans(struct jbd_journal *journal, struct jbd_trans *trans)
{
struct jbd_buf *jbd_buf, *tmp;
@ -1263,6 +1359,8 @@ void jbd_journal_cp_trans(struct jbd_journal *journal, struct jbd_trans *trans)
}
}
/**@brief Update the start block of the journal when
* all the contents in a transaction reach the disk.*/
static void jbd_trans_end_write(struct ext4_bcache *bc __unused,
struct ext4_buf *buf __unused,
int res,
@ -1312,6 +1410,9 @@ static void jbd_trans_end_write(struct ext4_bcache *bc __unused,
}
}
/**@brief Commit one transaction on transaction queue
* to the journal.
* @param journal current journal session.*/
void jbd_journal_commit_one(struct jbd_journal *journal)
{
int rc = EOK;
@ -1368,6 +1469,9 @@ Finish:
}
}
/**@brief Commit all the transactions on transaction queue
* to the journal.
* @param journal current journal session.*/
void jbd_journal_commit_all(struct jbd_journal *journal)
{
while (!TAILQ_EMPTY(&journal->trans_queue)) {

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