From: Michal Hocko <[email protected]> now that we have memalloc_nofs_{save,restore} api we can mark the whole transaction context as implicitly GFP_NOFS. All allocations will automatically inherit GFP_NOFS this way. This means that we do not have to mark any of those requests with GFP_NOFS and moreover all the ext4_kv[mz]alloc(GFP_NOFS) are also safe now because even the hardcoded GFP_KERNEL allocations deep inside the vmalloc will be NOFS now.
Reviewed-by: Jan Kara <[email protected]> Signed-off-by: Michal Hocko <[email protected]> --- fs/jbd2/transaction.c | 12 ++++++++++++ include/linux/jbd2.h | 2 ++ 2 files changed, 14 insertions(+) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 5e659ee08d6a..d8f09f34285f 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -29,6 +29,7 @@ #include <linux/backing-dev.h> #include <linux/bug.h> #include <linux/module.h> +#include <linux/sched/mm.h> #include <trace/events/jbd2.h> @@ -388,6 +389,11 @@ static int start_this_handle(journal_t *journal, handle_t *handle, rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_); jbd2_journal_free_transaction(new_transaction); + /* + * Make sure that no allocations done while the transaction is + * open is going to recurse back to the fs layer. + */ + handle->saved_alloc_context = memalloc_nofs_save(); return 0; } @@ -466,6 +472,7 @@ handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks, trace_jbd2_handle_start(journal->j_fs_dev->bd_dev, handle->h_transaction->t_tid, type, line_no, nblocks); + return handle; } EXPORT_SYMBOL(jbd2__journal_start); @@ -1760,6 +1767,11 @@ int jbd2_journal_stop(handle_t *handle) if (handle->h_rsv_handle) jbd2_journal_free_reserved(handle->h_rsv_handle); free_and_exit: + /* + * scope of th GFP_NOFS context is over here and so we can + * restore the original alloc context. + */ + memalloc_nofs_restore(handle->saved_alloc_context); jbd2_free_handle(handle); return err; } diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index dfaa1f4dcb0c..606b6bce3a5b 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -491,6 +491,8 @@ struct jbd2_journal_handle unsigned long h_start_jiffies; unsigned int h_requested_credits; + + unsigned int saved_alloc_context; }; -- 2.11.0 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
