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ocfs2: add ip_alloc_sem in direct IO to protect allocation changes

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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 <wangww631@huawei.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
WeiWei Wang 2015-09-04 15:44:23 -07:00 • committed by Linus Torvalds
parent 34237681e0
commit 6ab855a99b
1 changed files with 16 additions and 2 deletions
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18
fs/ocfs2/aops.c
View file

@ -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);