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Commit fe5f171b authored Jan 31, 2010 by Ryusuke Konishi

nilfs2: fix potential hang in nilfs_error on errors=remount-ro



nilfs_error() calls nilfs_detach_segment_constructor() if
errors=remount-ro option is specified, and this may lead to a hang due
to recursive locking of, for instance, nilfs->ns_segctor_sem and
others.

In this case, detaching segment constructor is not necessary because
read-only flag is set to the filesystem and further writes are
blocked.

This fixes the potential hang issue by removing the
nilfs_detach_segment_constructor() call from nilfs_error.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

parent 7512487e

fs/nilfs2/segment.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -2875,8 +2875,15 @@ int nilfs_attach_segment_constructor(struct nilfs_sb_info *sbi)
		struct the_nilfs *nilfs = sbi->s_nilfs;
		int err;

		/* Each field of nilfs_segctor is cleared through the initialization
		of super-block info */
		if (NILFS_SC(sbi)) {
		/*
		* This happens if the filesystem was remounted
		* read/write after nilfs_error degenerated it into a
		* read-only mount.
		*/
		nilfs_detach_segment_constructor(sbi);
		}

		sbi->s_sc_info = nilfs_segctor_new(sbi);
		if (!sbi->s_sc_info)
		return -ENOMEM;

fs/nilfs2/super.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -96,9 +96,6 @@ void nilfs_error(struct super_block sb, const char function,
		if (!(sb->s_flags & MS_RDONLY)) {
		struct the_nilfs *nilfs = sbi->s_nilfs;

		if (!nilfs_test_opt(sbi, ERRORS_CONT))
		nilfs_detach_segment_constructor(sbi);

		down_write(&nilfs->ns_sem);
		if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
		nilfs->ns_mount_state \|= NILFS_ERROR_FS;