The patch titled
Subject: ocfs2: fall back to buffer IO when append dio is disabled with file hole existing
has been added to the -mm tree. Its filename is
ocfs2-fall-back-to-buffer-io-when-append-dio-is-disabled-with-file-hole-existing.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-fall-back-to-buffer-io-when-append-dio-is-disabled-with-file-hole-existing.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-fall-back-to-buffer-io-when-append-dio-is-disabled-with-file-hole-existing.patch
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------------------------------------------------------
From: Changwei Ge <ge.changwei@xxxxxxx>
Subject: ocfs2: fall back to buffer IO when append dio is disabled with file hole existing
Before ocfs2 supporting allocating clusters while doing append-dio, all
append dio will fall back to buffer io to allocate clusters firstly.
Also, when it steps on a file hole, it will fall back to buffer io, too.
But for current code, writing to file hole will leverage dio to allocate
clusters. This is not right, since whether append-io is enabled tells the
capability whether ocfs2 can allocate space while doing dio.
So introduce file hole check function back into ocfs2. Once ocfs2 is
doing dio upon a file hole with append-dio disabled, it will fall back to
buffer IO to allocate clusters.
Link: http://lkml.kernel.org/r/63ADC13FD55D6546B7DECE290D39E373F1F5C2CE@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Changwei Ge <ge.changwei@xxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Joseph Qi <jiangqi903@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/aops.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 42 insertions(+), 2 deletions(-)
diff -puN fs/ocfs2/aops.c~ocfs2-fall-back-to-buffer-io-when-append-dio-is-disabled-with-file-hole-existing fs/ocfs2/aops.c
--- a/fs/ocfs2/aops.c~ocfs2-fall-back-to-buffer-io-when-append-dio-is-disabled-with-file-hole-existing
+++ a/fs/ocfs2/aops.c
@@ -2465,6 +2465,44 @@ static int ocfs2_dio_end_io(struct kiocb
return ret;
}
+/*
+ * Will look for holes and unwritten extents in the range starting at
+ * pos for count bytes (inclusive).
+ */
+static int ocfs2_check_range_for_holes(struct inode *inode, loff_t pos,
+ size_t count)
+{
+ int ret = 0;
+ unsigned int extent_flags;
+ u32 cpos, clusters, extent_len, phys_cpos;
+ struct super_block *sb = inode->i_sb;
+
+ cpos = pos >> OCFS2_SB(sb)->s_clustersize_bits;
+ clusters = ocfs2_clusters_for_bytes(sb, pos + count) - cpos;
+
+ while (clusters) {
+ ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &extent_len,
+ &extent_flags);
+ if (ret < 0) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ if (phys_cpos == 0 || (extent_flags & OCFS2_EXT_UNWRITTEN)) {
+ ret = 1;
+ break;
+ }
+
+ if (extent_len > clusters)
+ extent_len = clusters;
+
+ clusters -= extent_len;
+ cpos += extent_len;
+ }
+out:
+ return ret;
+}
+
static ssize_t ocfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
@@ -2480,8 +2518,10 @@ static ssize_t ocfs2_direct_IO(struct ki
return 0;
/* Fallback to buffered I/O if we do not support append dio. */
- if (iocb->ki_pos + iter->count > i_size_read(inode) &&
- !ocfs2_supports_append_dio(osb))
+ if (!ocfs2_supports_append_dio(osb) &&
+ (iocb->ki_pos + iter->count > i_size_read(inode) ||
+ ocfs2_check_range_for_holes(inode, iocb->ki_pos,
+ iter->count)))
return 0;
if (iov_iter_rw(iter) == READ)
_
Patches currently in -mm which might be from ge.changwei@xxxxxxx are
ocfs2-dlm-clean-dead-code-up.patch
ocfs2-cluster-neaten-a-member-of-o2net_msg_handler.patch
ocfs2-clean-dead-code-in-suballocc.patch
ocfs2-fall-back-to-buffer-io-when-append-dio-is-disabled-with-file-hole-existing.patch
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