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Subject[patch 49/71] ocfs2: Initialize the cluster were writing to in a non-sparse extend
2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Sunil Mushran <sunil.mushran@oracle.com>

commit e7432675f8ca868a4af365759a8d4c3779a3d922 upstream.

In a non-sparse extend, we correctly allocate (and zero) the clusters between
the old_i_size and pos, but we don't zero the portions of the cluster we're
writing to outside of pos<->len.

It handles clustersize > pagesize and blocksize < pagesize.

[Cleaned up by Joel Becker.]

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/ocfs2/aops.c | 66 +++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 47 insertions(+), 19 deletions(-)

--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -894,18 +894,17 @@ struct ocfs2_write_cluster_desc {
*/
unsigned c_new;
unsigned c_unwritten;
+ unsigned c_needs_zero;
};

-static inline int ocfs2_should_zero_cluster(struct ocfs2_write_cluster_desc *d)
-{
- return d->c_new || d->c_unwritten;
-}
-
struct ocfs2_write_ctxt {
/* Logical cluster position / len of write */
u32 w_cpos;
u32 w_clen;

+ /* First cluster allocated in a nonsparse extend */
+ u32 w_first_new_cpos;
+
struct ocfs2_write_cluster_desc w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];

/*
@@ -983,6 +982,7 @@ static int ocfs2_alloc_write_ctxt(struct
return -ENOMEM;

wc->w_cpos = pos >> osb->s_clustersize_bits;
+ wc->w_first_new_cpos = UINT_MAX;
cend = (pos + len - 1) >> osb->s_clustersize_bits;
wc->w_clen = cend - wc->w_cpos + 1;
get_bh(di_bh);
@@ -1217,20 +1217,18 @@ out:
*/
static int ocfs2_write_cluster(struct address_space *mapping,
u32 phys, unsigned int unwritten,
+ unsigned int should_zero,
struct ocfs2_alloc_context *data_ac,
struct ocfs2_alloc_context *meta_ac,
struct ocfs2_write_ctxt *wc, u32 cpos,
loff_t user_pos, unsigned user_len)
{
- int ret, i, new, should_zero = 0;
+ int ret, i, new;
u64 v_blkno, p_blkno;
struct inode *inode = mapping->host;
struct ocfs2_extent_tree et;

new = phys == 0 ? 1 : 0;
- if (new || unwritten)
- should_zero = 1;
-
if (new) {
u32 tmp_pos;

@@ -1341,7 +1339,9 @@ static int ocfs2_write_cluster_by_desc(s
local_len = osb->s_clustersize - cluster_off;

ret = ocfs2_write_cluster(mapping, desc->c_phys,
- desc->c_unwritten, data_ac, meta_ac,
+ desc->c_unwritten,
+ desc->c_needs_zero,
+ data_ac, meta_ac,
wc, desc->c_cpos, pos, local_len);
if (ret) {
mlog_errno(ret);
@@ -1391,14 +1391,14 @@ static void ocfs2_set_target_boundaries(
* newly allocated cluster.
*/
desc = &wc->w_desc[0];
- if (ocfs2_should_zero_cluster(desc))
+ if (desc->c_needs_zero)
ocfs2_figure_cluster_boundaries(osb,
desc->c_cpos,
&wc->w_target_from,
NULL);

desc = &wc->w_desc[wc->w_clen - 1];
- if (ocfs2_should_zero_cluster(desc))
+ if (desc->c_needs_zero)
ocfs2_figure_cluster_boundaries(osb,
desc->c_cpos,
NULL,
@@ -1466,13 +1466,28 @@ static int ocfs2_populate_write_desc(str
phys++;
}

+ /*
+ * If w_first_new_cpos is < UINT_MAX, we have a non-sparse
+ * file that got extended. w_first_new_cpos tells us
+ * where the newly allocated clusters are so we can
+ * zero them.
+ */
+ if (desc->c_cpos >= wc->w_first_new_cpos) {
+ BUG_ON(phys == 0);
+ desc->c_needs_zero = 1;
+ }
+
desc->c_phys = phys;
if (phys == 0) {
desc->c_new = 1;
+ desc->c_needs_zero = 1;
*clusters_to_alloc = *clusters_to_alloc + 1;
}
- if (ext_flags & OCFS2_EXT_UNWRITTEN)
+
+ if (ext_flags & OCFS2_EXT_UNWRITTEN) {
desc->c_unwritten = 1;
+ desc->c_needs_zero = 1;
+ }

num_clusters--;
}
@@ -1632,10 +1647,13 @@ static int ocfs2_expand_nonsparse_inode(
if (newsize <= i_size_read(inode))
return 0;

- ret = ocfs2_extend_no_holes(inode, newsize, newsize - len);
+ ret = ocfs2_extend_no_holes(inode, newsize, pos);
if (ret)
mlog_errno(ret);

+ wc->w_first_new_cpos =
+ ocfs2_clusters_for_bytes(inode->i_sb, i_size_read(inode));
+
return ret;
}

@@ -1644,7 +1662,7 @@ int ocfs2_write_begin_nolock(struct addr
struct page **pagep, void **fsdata,
struct buffer_head *di_bh, struct page *mmap_page)
{
- int ret, credits = OCFS2_INODE_UPDATE_CREDITS;
+ int ret, cluster_of_pages, credits = OCFS2_INODE_UPDATE_CREDITS;
unsigned int clusters_to_alloc, extents_to_split;
struct ocfs2_write_ctxt *wc;
struct inode *inode = mapping->host;
@@ -1722,8 +1740,19 @@ int ocfs2_write_begin_nolock(struct addr

}

- ocfs2_set_target_boundaries(osb, wc, pos, len,
- clusters_to_alloc + extents_to_split);
+ /*
+ * We have to zero sparse allocated clusters, unwritten extent clusters,
+ * and non-sparse clusters we just extended. For non-sparse writes,
+ * we know zeros will only be needed in the first and/or last cluster.
+ */
+ if (clusters_to_alloc || extents_to_split ||
+ wc->w_desc[0].c_needs_zero ||
+ wc->w_desc[wc->w_clen - 1].c_needs_zero)
+ cluster_of_pages = 1;
+ else
+ cluster_of_pages = 0;
+
+ ocfs2_set_target_boundaries(osb, wc, pos, len, cluster_of_pages);

handle = ocfs2_start_trans(osb, credits);
if (IS_ERR(handle)) {
@@ -1756,8 +1785,7 @@ int ocfs2_write_begin_nolock(struct addr
* extent.
*/
ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
- clusters_to_alloc + extents_to_split,
- mmap_page);
+ cluster_of_pages, mmap_page);
if (ret) {
mlog_errno(ret);
goto out_quota;



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