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udf: Fix deadlock between writeback and udf_setsize() 

udf_setsize() called truncate_setsize() with i_data_sem held. Thus
truncate_pagecache() called from truncate_setsize() could lock a page
under i_data_sem which can deadlock as page lock ranks below
i_data_sem - e. g. writeback can hold page lock and try to acquire
i_data_sem to map a block.

Fix the problem by moving truncate_setsize() calls from under
i_data_sem. It is safe for us to change i_size without holding
i_data_sem as all the places that depend on i_size being stable already
hold inode_lock.

CC: stable@vger.kernel.org
Fixes: 7e49b6f248
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2017-06-13 16:20:25 +02:00
parent 146c4ad6ec
commit f2e9535589
1 changed files with 2 additions and 2 deletions
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4
fs/udf/inode.c
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@ -1222,8 +1222,8 @@ int udf_setsize(struct inode *inode, loff_t newsize)
return err;
}
set_size:
truncate_setsize(inode, newsize);
up_write(&iinfo->i_data_sem);
truncate_setsize(inode, newsize);
} else {
if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
down_write(&iinfo->i_data_sem);
@ -1240,9 +1240,9 @@ int udf_setsize(struct inode *inode, loff_t newsize)
udf_get_block);
if (err)
return err;
truncate_setsize(inode, newsize);
down_write(&iinfo->i_data_sem);
udf_clear_extent_cache(inode);
truncate_setsize(inode, newsize);
udf_truncate_extents(inode);
up_write(&iinfo->i_data_sem);
}