[Ocfs2-devel] [PATCH 1/1] ocfs2: Initialize the cluster we're writing to in a non-sparse extend
Joel Becker
Joel.Becker at oracle.com
Sun Aug 2 15:05:24 PDT 2009
On Sun, Aug 02, 2009 at 01:04:10PM -0700, Sunil Mushran wrote:
> 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.
I'd do it more like this. Rather than have magic based on
c_new, c_unwritten, and c_needs_zero_but_is_only_set_for_nonsparse,
let's set c_needs_zero for all types that need zeroing. Then we can
just trust c_needs_zero everywhere. I saw your attempt at optimization,
setting c_needs_zero on only the first and last cluster of a non-sparse
write, but it's not necessary. ocfs2_write_cluster() will figure out
that user_pos and user_len cover the entire cluster.
Joel
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index e511df1..8b853e5 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -893,20 +893,18 @@ struct ocfs2_write_cluster_desc {
* Give this a unique field because c_phys eventually gets
* filled.
*/
- unsigned c_new;
- unsigned c_unwritten;
+ unsigned c_new; /* needs to be allocated */
+ unsigned c_unwritten; /* unwritten extent */
+ unsigned c_needs_zero; /* nonsparse allocation */
};
-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;
+ u32 w_first_new_cpos;
+
struct ocfs2_write_cluster_desc w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
/*
@@ -984,6 +982,7 @@ static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
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);
@@ -1218,19 +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;
@@ -1342,7 +1340,9 @@ static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
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);
@@ -1392,14 +1392,14 @@ static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
* 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,
@@ -1467,17 +1467,41 @@ static int ocfs2_populate_write_desc(struct inode *inode,
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--;
}
+ mlog(0, "inode %llu, wc 0x%p, cpos %u, clen %u, fcpos %u\n",
+ OCFS2_I(inode)->ip_blkno, wc, wc->w_cpos, wc->w_clen,
+ wc->w_first_new_cpos);
+
+ for (i = 0; i < wc->w_clen; i++) {
+ desc = &wc->w_desc[i];
+ mlog(0, "%d => cpos %u, phys %u, new %u, unw %u, zero %u\n",
+ i, desc->c_cpos, desc->c_phys, desc->c_new,
+ desc->c_unwritten, desc->c_needs_zero);
+ }
+
ret = 0;
out:
return ret;
@@ -1633,10 +1657,13 @@ static int ocfs2_expand_nonsparse_inode(struct inode *inode, loff_t pos,
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_align_bytes_to_clusters(inode->i_sb, i_size_read(inode));
+
return ret;
}
--
#!/bin/perl -sp0777i<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<j]dsj
$/=unpack('H*',$_);$_=`echo 16dio\U$k"SK$/SM$n\EsN0p[lN*1
lK[d2%Sa2/d0$^Ixp"|dc`;s/\W//g;$_=pack('H*',/((..)*)$/)
Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127
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