From: WeiWei Wang <wangww...@huawei.com>
Subject: 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: Weiwei Wang <wangww...@huawei.com>
Cc: Mark Fasheh <mfas...@suse.com>
Cc: Joel Becker <jl...@evilplan.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---
fs/ocfs2/aops.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff -puN
fs/ocfs2/aops.c~ocfs2-add-ip_alloc_sem-in-direct-io-to-protect-allocation-changes
fs/ocfs2/aops.c
---
a/fs/ocfs2/aops.c~ocfs2-add-ip_alloc_sem-in-direct-io-to-protect-allocation-changes
+++ a/fs/ocfs2/aops.c
@@ -533,10 +533,14 @@ static int ocfs2_direct_IO_get_blocks(st
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(st
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(st
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(st
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(str
/* 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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