jbd2: make b_frozen_data allocation always succeed

The b_frozen_data allocation should not be failed during journal
committing process, otherwise jbd2 will abort.
Since commit 490c1b4("jbd2: do not fail journal because of
frozen_buffer allocation failure") already added '__GFP_NOFAIL' flag
in do_get_write_access(), just add '__GFP_NOFAIL' flag for all allocations
in jbd2_journal_write_metadata_buffer(), like 'new_bh' allocation does.
Besides, remove all error handling branches for do_get_write_access().

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20241012085530.2147846-1-chengzhihao@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: Zhihao Cheng

fs/jbd2/commit.c

@@ -662,10 +662,6 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 		JBUFFER_TRACE(jh, "ph3: write metadata");
 		escape = jbd2_journal_write_metadata_buffer(commit_transaction,
 						jh, &wbuf[bufs], blocknr);
-		if (escape < 0) {
-			jbd2_journal_abort(journal, escape);
-			continue;
-		}
 		jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 
 		/* Record the new block's tag in the current descriptor

fs/jbd2/journal.c

@@ -318,7 +318,6 @@ static inline void jbd2_data_do_escape(char *data)
  *
  *
  * Return value:
- *  <0: Error
  *  =0: Finished OK without escape
  *  =1: Finished OK with escape
  */
@@ -386,12 +385,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 			goto escape_done;
 
 		spin_unlock(&jh_in->b_state_lock);
-		tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
-		if (!tmp) {
-			brelse(new_bh);
-			free_buffer_head(new_bh);
-			return -ENOMEM;
-		}
+		tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS | __GFP_NOFAIL);
 		spin_lock(&jh_in->b_state_lock);
 		if (jh_in->b_frozen_data) {
 			jbd2_free(tmp, bh_in->b_size);