From d7bdb996aef67ea24c62707ca4e29b07025e9683 Mon Sep 17 00:00:00 2001 From: Sougata Santra Date: Thu, 3 Apr 2014 14:50:34 -0700 Subject: [PATCH] fs/hfsplus/extents.c: fix concurrent acess of alloc_blocks Concurrent access to alloc_blocks in hfsplus_inode_info() is protected by extents_lock mutex. This patch fixes two instances where alloc_blocks modification was not protected with this lock. This fixes possible allocation bitmap corruption in race conditions while extending and truncating files. [akpm@linux-foundation.org: take extents_lock before taking a copy of ->alloc_blocks] [akpm@linux-foundation.org: remove now-unused label `out'] Signed-off-by: Sougata Santra Reviewed-by: Christoph Hellwig Cc: Vyacheslav Dubeyko Cc: Alexey Khoroshilov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/hfsplus/extents.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c index 136d860cd746..a7aafb35b624 100644 --- a/fs/hfsplus/extents.c +++ b/fs/hfsplus/extents.c @@ -496,11 +496,13 @@ int hfsplus_file_extend(struct inode *inode) goto insert_extent; } out: - mutex_unlock(&hip->extents_lock); if (!res) { hip->alloc_blocks += len; + mutex_unlock(&hip->extents_lock); hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY); + return 0; } + mutex_unlock(&hip->extents_lock); return res; insert_extent: @@ -554,11 +556,13 @@ void hfsplus_file_truncate(struct inode *inode) blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >> HFSPLUS_SB(sb)->alloc_blksz_shift; + + mutex_lock(&hip->extents_lock); + alloc_cnt = hip->alloc_blocks; if (blk_cnt == alloc_cnt) - goto out; + goto out_unlock; - mutex_lock(&hip->extents_lock); res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd); if (res) { mutex_unlock(&hip->extents_lock); @@ -590,10 +594,10 @@ void hfsplus_file_truncate(struct inode *inode) hfs_brec_remove(&fd); } hfs_find_exit(&fd); - mutex_unlock(&hip->extents_lock); hip->alloc_blocks = blk_cnt; -out: +out_unlock: + mutex_unlock(&hip->extents_lock); hip->phys_size = inode->i_size; hip->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; -- 2.20.1