Good day,
under some quite high load, jbd can hit J_ASSERT(journal->j_free > 1)
in journal_next_log_block(). The cause is the following:
journal_commit_transaction()
{
struct buffer_head *wbuf[64];
....
/* If there's no more to do, or if the descriptor is full,
let the IO rip! */
if (bufs == ARRAY_SIZE(wbuf) ||
commit_transaction->t_buffers == NULL ||
space_left < sizeof(journal_block_tag_t) + 16) {
so, the real limit isn't size of journal descriptor, but wbuf.
__log_space_left()
{
/*
* Be pessimistic here about the number of those free blocks which
* might be required for log descriptor control blocks.
*/
#define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
left -= MIN_LOG_RESERVED_BLOCKS;
so, jbd expects upto 32 blocks to be used for internal purpose. but
with 64 blocks a descriptor limit we easily can break the limit.
The fix allocates wbuf in journal_init_dev(). That's enough because
we have only commit thread per filesystem.
thank, Alex
The journal_commit_transaction() generates too many descriptor blocks
because static array wbuf can hold 64 blocks only. The fix is to have
persistent array big enough to hold max. possible blocks.
Signed-off-by: Alex Tomas <[EMAIL PROTECTED]>
Index: linux-2.6.7/include/linux/jbd.h
===================================================================
--- linux-2.6.7.orig/include/linux/jbd.h 2004-08-26 17:12:16.000000000
+0400
+++ linux-2.6.7/include/linux/jbd.h 2005-01-19 17:08:33.144512008 +0300
@@ -826,6 +826,12 @@
struct jbd_revoke_table_s *j_revoke_table[2];
/*
+ * array of bhs for journal_commit_transaction
+ */
+ struct buffer_head **j_wbuf;
+ int j_wbufsize;
+
+ /*
* An opaque pointer to fs-private information. ext3 puts its
* superblock pointer here
*/
Index: linux-2.6.7/fs/jbd/commit.c
===================================================================
--- linux-2.6.7.orig/fs/jbd/commit.c 2004-08-26 17:12:40.000000000 +0400
+++ linux-2.6.7/fs/jbd/commit.c 2005-01-19 17:28:32.965111552 +0300
@@ -103,7 +103,7 @@
{
transaction_t *commit_transaction;
struct journal_head *jh, *new_jh, *descriptor;
- struct buffer_head *wbuf[64];
+ struct buffer_head **wbuf = journal->j_wbuf;
int bufs;
int flags;
int err;
@@ -271,7 +283,7 @@
BUFFER_TRACE(bh, "start journal writeout");
get_bh(bh);
wbuf[bufs++] = bh;
- if (bufs == ARRAY_SIZE(wbuf)) {
+ if (bufs == journal->j_wbufsize) {
jbd_debug(2, "submit %d writes\n",
bufs);
spin_unlock(&journal->j_list_lock);
@@ -488,7 +500,7 @@
/* If there's no more to do, or if the descriptor is full,
let the IO rip! */
- if (bufs == ARRAY_SIZE(wbuf) ||
+ if (bufs == journal->j_wbufsize ||
commit_transaction->t_buffers == NULL ||
space_left < sizeof(journal_block_tag_t) + 16) {
Index: linux-2.6.7/fs/jbd/journal.c
===================================================================
--- linux-2.6.7.orig/fs/jbd/journal.c 2005-01-19 12:07:59.000000000 +0300
+++ linux-2.6.7/fs/jbd/journal.c 2005-01-19 17:11:08.589880720 +0300
@@ -687,6 +687,7 @@
{
journal_t *journal = journal_init_common();
struct buffer_head *bh;
+ int n;
if (!journal)
return NULL;
@@ -702,6 +703,17 @@
journal->j_sb_buffer = bh;
journal->j_superblock = (journal_superblock_t *)bh->b_data;
+ /* journal descriptor can store upto n blocks -bzzz */
+ n = journal->j_blocksize / sizeof(journal_block_tag_t);
+ journal->j_wbufsize = n;
+ journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
+ if (!journal->j_wbuf) {
+ printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
+ __FUNCTION__);
+ kfree(journal);
+ journal = NULL;
+ }
+
return journal;
}
@@ -717,7 +729,7 @@
{
struct buffer_head *bh;
journal_t *journal = journal_init_common();
- int err;
+ int err, n;
unsigned long blocknr;
if (!journal)
@@ -734,6 +746,17 @@
journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
journal->j_blocksize = inode->i_sb->s_blocksize;
+ /* journal descriptor can store upto n blocks -bzzz */
+ n = journal->j_blocksize / sizeof(journal_block_tag_t);
+ journal->j_wbufsize = n;
+ journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
+ if (!journal->j_wbuf) {
+ printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
+ __FUNCTION__);
+ kfree(journal);
+ return NULL;
+ }
+
err = journal_bmap(journal, 0, &blocknr);
/* If that failed, give up */
if (err) {
@@ -1107,6 +1130,10 @@
iput(journal->j_inode);
if (journal->j_revoke)
journal_destroy_revoke(journal);
+ if (journal->j_wbuf) {
+ kfree(journal->j_wbuf);
+ journal->j_wbuf = NULL;
+ }
kfree(journal);
}
-
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