Commit 6ab855a9 authored by WeiWei Wang's avatar WeiWei Wang Committed by Linus Torvalds
Browse files

ocfs2: add ip_alloc_sem in direct IO to protect allocation changes 



In ocfs2, ip_alloc_sem is used to protect allocation changes on the
node.  In direct IO, we add ip_alloc_sem to protect date consistent
between direct-io and ocfs2_truncate_file race (buffer io use
ip_alloc_sem already).  Although inode->i_mutex lock is used to avoid
concurrency of above situation, i think ip_alloc_sem is still needed
because protect allocation changes is significant.

Other filesystem like ext4 also uses rw_semaphore to protect data
consistent between get_block-vs-truncate race by other means, So
ip_alloc_sem in ocfs2 direct io is needed.

Signed-off-by: default avatarWeiwei Wang <wangww631@huawei.com>
Signed-off-by: default avatarMark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 34237681

fs/ocfs2/aops.c

+16 −2
Original line number Diff line number Diff line
@@ -533,10 +533,14 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, 


	inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));



	down_read(&OCFS2_I(inode)->ip_alloc_sem);



	/* This figures out the size of the next contiguous block, and

	 * our logical offset */

	ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,

					  &contig_blocks, &ext_flags);

	up_read(&OCFS2_I(inode)->ip_alloc_sem);



	if (ret) {

		mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",

		     (unsigned long long)iblock);
@@ -557,6 +561,8 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, 


		alloc_locked = 1;



		down_write(&OCFS2_I(inode)->ip_alloc_sem);



		/* fill hole, allocate blocks can't be larger than the size

		 * of the hole */

		clusters_to_alloc = ocfs2_clusters_for_bytes(inode->i_sb, len);
@@ -569,6 +575,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, 
		ret = ocfs2_extend_allocation(inode, cpos,

				clusters_to_alloc, 0);

		if (ret < 0) {

			up_write(&OCFS2_I(inode)->ip_alloc_sem);

			mlog_errno(ret);

			goto bail;

		}
@@ -576,11 +583,13 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, 
		ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,

				&contig_blocks, &ext_flags);

		if (ret < 0) {

			up_write(&OCFS2_I(inode)->ip_alloc_sem);

			mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",

					(unsigned long long)iblock);

			ret = -EIO;

			goto bail;

		}

		up_write(&OCFS2_I(inode)->ip_alloc_sem);

	}



	/*
@@ -835,12 +844,17 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb, 


		/* zeroing out the previously allocated cluster tail

		 * that but not zeroed */

		if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))

		if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {

			down_read(&OCFS2_I(inode)->ip_alloc_sem);

			ret = ocfs2_direct_IO_zero_extend(osb, inode, offset,

					zero_len_tail, cluster_align_tail);

		else

			up_read(&OCFS2_I(inode)->ip_alloc_sem);

		} else {

			down_write(&OCFS2_I(inode)->ip_alloc_sem);

			ret = ocfs2_direct_IO_extend_no_holes(osb, inode,

					offset);

			up_write(&OCFS2_I(inode)->ip_alloc_sem);

		}

		if (ret < 0) {

			mlog_errno(ret);

			ocfs2_inode_unlock(inode, 1);

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