Commit a50527b1 authored Dec 02, 2011 by Jan Kara Committed by Wu Fengguang Dec 02, 2011

fs: Make write(2) interruptible by a fatal signal



Currently write(2) to a file is not interruptible by any signal.
Sometimes this is desirable, e.g. when you want to quickly kill a
process hogging your disk. Also, with commit 499d05ec ("mm: Make
task in balance_dirty_pages() killable"), it's necessary to abort the
current write accordingly to avoid it quickly dirtying lots more pages
at unthrottled rate.

This patch makes write interruptible by SIGKILL. We do not allow write
to be interruptible by any other signal because that has larger
potential of screwing some badly written applications.

Reported-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Tested-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Acked-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

parent 786228ab

mm/filemap.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2407,7 +2407,6 @@ static ssize_t generic_perform_write(struct file *file,
		iov_iter_count(i));

		again:

		/*
		* Bring in the user page that we will copy from _first_.
		* Otherwise there's a nasty deadlock on copying from the
		@@ -2463,7 +2462,10 @@ again:
		written += copied;

		balance_dirty_pages_ratelimited(mapping);

		if (fatal_signal_pending(current)) {
		status = -EINTR;
		break;
		}
		} while (iov_iter_count(i));

		return written ? written : status;

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