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ocfs2: Zero the tail cluster when extending past i_size. 

ocfs2's allocation unit is the cluster.  This can be larger than a block
or even a memory page.  This means that a file may have many blocks in
its last extent that are beyond the block containing i_size.  There also
may be more unwritten extents after that.

When ocfs2 grows a file, it zeros the entire cluster in order to ensure
future i_size growth will see cleared blocks.  Unfortunately,
block_write_full_page() drops the pages past i_size.  This means that
ocfs2 is actually leaking garbage data into the tail end of that last
cluster.  This is a bug.

We adjust ocfs2_write_begin_nolock() and ocfs2_extend_file() to detect
when a write or truncate is past i_size.  They will use
ocfs2_zero_extend() to ensure the data is properly zeroed.

Older versions of ocfs2_zero_extend() simply zeroed every block between
i_size and the zeroing position.  This presumes three things:

1) There is allocation for all of these blocks.
2) The extents are not unwritten.
3) The extents are not refcounted.

(1) and (2) hold true for non-sparse filesystems, which used to be the
only users of ocfs2_zero_extend().  (3) is another bug.

Since we're now using ocfs2_zero_extend() for sparse filesystems as
well, we teach ocfs2_zero_extend() to check every extent between
i_size and the zeroing position.  If the extent is unwritten, it is
ignored.  If it is refcounted, it is CoWed.  Then it is zeroed.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Cc: stable@kernel.org
This commit is contained in:
Joel Becker 2010-07-01 15:13:31 -07:00
parent a4bfb4cf11
commit 5693486bad
6 changed files with 207 additions and 54 deletions
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42
fs/ocfs2/aops.c
View File

@ -196,15 +196,14 @@ int ocfs2_get_block(struct inode *inode, sector_t iblock,
dump_stack();
goto bail;
}
past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
(unsigned long long)past_eof);
if (create && (iblock >= past_eof))
set_buffer_new(bh_result);
}
past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
(unsigned long long)past_eof);
if (create && (iblock >= past_eof))
set_buffer_new(bh_result);
bail:
if (err < 0)
err = -EIO;
@ -1590,21 +1589,20 @@ out:
* write path can treat it as an non-allocating write, which has no
* special case code for sparse/nonsparse files.
*/
static int ocfs2_expand_nonsparse_inode(struct inode *inode, loff_t pos,
unsigned len,
static int ocfs2_expand_nonsparse_inode(struct inode *inode,
struct buffer_head *di_bh,
loff_t pos, unsigned len,
struct ocfs2_write_ctxt *wc)
{
int ret;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
loff_t newsize = pos + len;
if (ocfs2_sparse_alloc(osb))
return 0;
BUG_ON(ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
if (newsize <= i_size_read(inode))
return 0;
ret = ocfs2_extend_no_holes(inode, newsize, pos);
ret = ocfs2_extend_no_holes(inode, di_bh, newsize, pos);
if (ret)
mlog_errno(ret);
@ -1614,6 +1612,18 @@ static int ocfs2_expand_nonsparse_inode(struct inode *inode, loff_t pos,
return ret;
}
static int ocfs2_zero_tail(struct inode *inode, struct buffer_head *di_bh,
loff_t pos)
{
int ret = 0;
BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
if (pos > i_size_read(inode))
ret = ocfs2_zero_extend(inode, di_bh, pos);
return ret;
}
int ocfs2_write_begin_nolock(struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata,
@ -1649,7 +1659,11 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
}
}
ret = ocfs2_expand_nonsparse_inode(inode, pos, len, wc);
if (ocfs2_sparse_alloc(osb))
ret = ocfs2_zero_tail(inode, di_bh, pos);
else
ret = ocfs2_expand_nonsparse_inode(inode, di_bh, pos, len,
wc);
if (ret) {
mlog_errno(ret);
goto out;

201
fs/ocfs2/file.c
View File

@ -787,6 +787,11 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
if (!zero_to)
zero_to = PAGE_CACHE_SIZE;
mlog(0,
"abs_from = %llu, abs_to = %llu, index = %lu, zero_from = %u, zero_to = %u\n",
(unsigned long long)abs_from, (unsigned long long)abs_to,
index, zero_from, zero_to);
/* We know that zero_from is block aligned */
for (block_start = zero_from; block_start < zero_to;
block_start = block_end) {
@ -833,25 +838,114 @@ out:
return ret;
}
static int ocfs2_zero_extend(struct inode *inode,
u64 zero_to_size)
/*
* Find the next range to zero. We do this in terms of bytes because
* that's what ocfs2_zero_extend() wants, and it is dealing with the
* pagecache. We may return multiple extents.
*
* zero_start and zero_end are ocfs2_zero_extend()s current idea of what
* needs to be zeroed. range_start and range_end return the next zeroing
* range. A subsequent call should pass the previous range_end as its
* zero_start. If range_end is 0, there's nothing to do.
*
* Unwritten extents are skipped over. Refcounted extents are CoWd.
*/
static int ocfs2_zero_extend_get_range(struct inode *inode,
struct buffer_head *di_bh,
u64 zero_start, u64 zero_end,
u64 *range_start, u64 *range_end)
{
int ret = 0;
u64 start_off, next_off;
struct super_block *sb = inode->i_sb;
int rc = 0, needs_cow = 0;
u32 p_cpos, zero_clusters = 0;
u32 zero_cpos =
zero_start >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
u32 last_cpos = ocfs2_clusters_for_bytes(inode->i_sb, zero_end);
unsigned int num_clusters = 0;
unsigned int ext_flags = 0;
start_off = ocfs2_align_bytes_to_blocks(sb, i_size_read(inode));
while (start_off < zero_to_size) {
next_off = (start_off & PAGE_CACHE_MASK) + PAGE_CACHE_SIZE;
if (next_off > zero_to_size)
next_off = zero_to_size;
ret = ocfs2_write_zero_page(inode, start_off, next_off);
if (ret < 0) {
mlog_errno(ret);
while (zero_cpos < last_cpos) {
rc = ocfs2_get_clusters(inode, zero_cpos, &p_cpos,
&num_clusters, &ext_flags);
if (rc) {
mlog_errno(rc);
goto out;
}
start_off = next_off;
if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
zero_clusters = num_clusters;
if (ext_flags & OCFS2_EXT_REFCOUNTED)
needs_cow = 1;
break;
}
zero_cpos += num_clusters;
}
if (!zero_clusters) {
*range_end = 0;
goto out;
}
while ((zero_cpos + zero_clusters) < last_cpos) {
rc = ocfs2_get_clusters(inode, zero_cpos + zero_clusters,
&p_cpos, &num_clusters,
&ext_flags);
if (rc) {
mlog_errno(rc);
goto out;
}
if (!p_cpos || (ext_flags & OCFS2_EXT_UNWRITTEN))
break;
if (ext_flags & OCFS2_EXT_REFCOUNTED)
needs_cow = 1;
zero_clusters += num_clusters;
}
if ((zero_cpos + zero_clusters) > last_cpos)
zero_clusters = last_cpos - zero_cpos;
if (needs_cow) {
rc = ocfs2_refcount_cow(inode, di_bh, zero_cpos, zero_clusters,
UINT_MAX);
if (rc) {
mlog_errno(rc);
goto out;
}
}
*range_start = ocfs2_clusters_to_bytes(inode->i_sb, zero_cpos);
*range_end = ocfs2_clusters_to_bytes(inode->i_sb,
zero_cpos + zero_clusters);
out:
return rc;
}
/*
* Zero one range returned from ocfs2_zero_extend_get_range(). The caller
* has made sure that the entire range needs zeroing.
*/
static int ocfs2_zero_extend_range(struct inode *inode, u64 range_start,
u64 range_end)
{
int rc = 0;
u64 next_pos;
u64 zero_pos = range_start;
mlog(0, "range_start = %llu, range_end = %llu\n",
(unsigned long long)range_start,
(unsigned long long)range_end);
BUG_ON(range_start >= range_end);
while (zero_pos < range_end) {
next_pos = (zero_pos & PAGE_CACHE_MASK) + PAGE_CACHE_SIZE;
if (next_pos > range_end)
next_pos = range_end;
rc = ocfs2_write_zero_page(inode, zero_pos, next_pos);
if (rc < 0) {
mlog_errno(rc);
break;
}
zero_pos = next_pos;
/*
* Very large extends have the potential to lock up
@ -860,16 +954,63 @@ static int ocfs2_zero_extend(struct inode *inode,
cond_resched();
}
out:
return rc;
}
int ocfs2_zero_extend(struct inode *inode, struct buffer_head *di_bh,
loff_t zero_to_size)
{
int ret = 0;
u64 zero_start, range_start = 0, range_end = 0;
struct super_block *sb = inode->i_sb;
zero_start = ocfs2_align_bytes_to_blocks(sb, i_size_read(inode));
mlog(0, "zero_start %llu for i_size %llu\n",
(unsigned long long)zero_start,
(unsigned long long)i_size_read(inode));
while (zero_start < zero_to_size) {
ret = ocfs2_zero_extend_get_range(inode, di_bh, zero_start,
zero_to_size,
&range_start,
&range_end);
if (ret) {
mlog_errno(ret);
break;
}
if (!range_end)
break;
/* Trim the ends */
if (range_start < zero_start)
range_start = zero_start;
if (range_end > zero_to_size)
range_end = zero_to_size;
ret = ocfs2_zero_extend_range(inode, range_start,
range_end);
if (ret) {
mlog_errno(ret);
break;
}
zero_start = range_end;
}
return ret;
}
int ocfs2_extend_no_holes(struct inode *inode, u64 new_i_size, u64 zero_to)
int ocfs2_extend_no_holes(struct inode *inode, struct buffer_head *di_bh,
u64 new_i_size, u64 zero_to)
{
int ret;
u32 clusters_to_add;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
/*
* Only quota files call this without a bh, and they can't be
* refcounted.
*/
BUG_ON(!di_bh && (oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
BUG_ON(!di_bh && !(oi->ip_flags & OCFS2_INODE_SYSTEM_FILE));
clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size);
if (clusters_to_add < oi->ip_clusters)
clusters_to_add = 0;
@ -890,7 +1031,7 @@ int ocfs2_extend_no_holes(struct inode *inode, u64 new_i_size, u64 zero_to)
* still need to zero the area between the old i_size and the
* new i_size.
*/
ret = ocfs2_zero_extend(inode, zero_to);
ret = ocfs2_zero_extend(inode, di_bh, zero_to);
if (ret < 0)
mlog_errno(ret);
@ -912,27 +1053,15 @@ static int ocfs2_extend_file(struct inode *inode,
goto out;
if (i_size_read(inode) == new_i_size)
goto out;
goto out;
BUG_ON(new_i_size < i_size_read(inode));
/*
* Fall through for converting inline data, even if the fs
* supports sparse files.
*
* The check for inline data here is legal - nobody can add
* the feature since we have i_mutex. We must check it again
* after acquiring ip_alloc_sem though, as paths like mmap
* might have raced us to converting the inode to extents.
*/
if (!(oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
&& ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
goto out_update_size;
/*
* The alloc sem blocks people in read/write from reading our
* allocation until we're done changing it. We depend on
* i_mutex to block other extend/truncate calls while we're
* here.
* here. We even have to hold it for sparse files because there
* might be some tail zeroing.
*/
down_write(&oi->ip_alloc_sem);
@ -949,14 +1078,16 @@ static int ocfs2_extend_file(struct inode *inode,
ret = ocfs2_convert_inline_data_to_extents(inode, di_bh);
if (ret) {
up_write(&oi->ip_alloc_sem);
mlog_errno(ret);
goto out;
}
}
if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
ret = ocfs2_extend_no_holes(inode, new_i_size, new_i_size);
if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
ret = ocfs2_zero_extend(inode, di_bh, new_i_size);
else
ret = ocfs2_extend_no_holes(inode, di_bh, new_i_size,
new_i_size);
up_write(&oi->ip_alloc_sem);

6
fs/ocfs2/file.h
View File

@ -54,8 +54,10 @@ int ocfs2_add_inode_data(struct ocfs2_super *osb,
int ocfs2_simple_size_update(struct inode *inode,
struct buffer_head *di_bh,
u64 new_i_size);
int ocfs2_extend_no_holes(struct inode *inode, u64 new_i_size,
u64 zero_to);
int ocfs2_extend_no_holes(struct inode *inode, struct buffer_head *di_bh,
u64 new_i_size, u64 zero_to);
int ocfs2_zero_extend(struct inode *inode, struct buffer_head *di_bh,
loff_t zero_to);
int ocfs2_setattr(struct dentry *dentry, struct iattr *attr);
int ocfs2_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat);

2
fs/ocfs2/quota_global.c
View File

@ -775,7 +775,7 @@ static int ocfs2_acquire_dquot(struct dquot *dquot)
* locking allocators ranks above a transaction start
*/
WARN_ON(journal_current_handle());
status = ocfs2_extend_no_holes(gqinode,
status = ocfs2_extend_no_holes(gqinode, NULL,
gqinode->i_size + (need_alloc << sb->s_blocksize_bits),
gqinode->i_size);
if (status < 0)

4
fs/ocfs2/quota_local.c
View File

@ -971,7 +971,7 @@ static struct ocfs2_quota_chunk *ocfs2_local_quota_add_chunk(
u64 p_blkno;
/* We are protected by dqio_sem so no locking needed */
status = ocfs2_extend_no_holes(lqinode,
status = ocfs2_extend_no_holes(lqinode, NULL,
lqinode->i_size + 2 * sb->s_blocksize,
lqinode->i_size);
if (status < 0) {
@ -1114,7 +1114,7 @@ static struct ocfs2_quota_chunk *ocfs2_extend_local_quota_file(
return ocfs2_local_quota_add_chunk(sb, type, offset);
/* We are protected by dqio_sem so no locking needed */
status = ocfs2_extend_no_holes(lqinode,
status = ocfs2_extend_no_holes(lqinode, NULL,
lqinode->i_size + sb->s_blocksize,
lqinode->i_size);
if (status < 0) {

6
fs/ocfs2/refcounttree.c
View File

@ -4166,6 +4166,12 @@ static int __ocfs2_reflink(struct dentry *old_dentry,
struct inode *inode = old_dentry->d_inode;
struct buffer_head *new_bh = NULL;
if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE) {
ret = -EINVAL;
mlog_errno(ret);
goto out;
}
ret = filemap_fdatawrite(inode->i_mapping);
if (ret) {
mlog_errno(ret);