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jbd2: mark the transaction context with the scope GFP_NOFS context

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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.

[akpm@linux-foundation.org: tweak comments]
Link: http://lkml.kernel.org/r/20170306131408.9828-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2017-05-03 14:53:22 -07:00 committed by Linus Torvalds
parent 9ba1fb2c60
commit 81378da64d
2 changed files with 14 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

12
fs/jbd2/transaction.c
View file

@ -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);
/*
* Ensure that no allocations done while the transaction is open are
* 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 the 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;
}

2
include/linux/jbd2.h
View file

@ -491,6 +491,8 @@ struct jbd2_journal_handle
unsigned long h_start_jiffies;
unsigned int h_requested_credits;
unsigned int saved_alloc_context;
};