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authorSage Weil <sage@newdream.net>2011-07-26 11:27:34 -0700
committerSage Weil <sage@newdream.net>2011-07-26 11:27:34 -0700
commitd8de9ab63a57326d21154c13c365f949f53ce8e1 (patch)
tree283aac6bf2cc91a772d9cc04c97f46f60267e4c5
parent4cf9d544631c92809cb94ea680c71df56e9437aa (diff)
ceph: avoid carrying Fw cap during write into page cache
The generic_file_aio_write call may block on balance_dirty_pages while we flush data to the OSDs. If we hold a reference to the FILE_WR cap during that interval revocation by the MDS (e.g., to do a stat(2)) may be very slow. Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
-rw-r--r--fs/ceph/file.c22
1 files changed, 19 insertions, 3 deletions
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 44e4fe9fba02..6c90cf090601 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -713,7 +713,7 @@ retry_snap:
want = CEPH_CAP_FILE_BUFFER;
ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, &got, endoff);
if (ret < 0)
- goto out;
+ goto out_put;
dout("aio_write %p %llx.%llx %llu~%u got cap refs on %s\n",
inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
@@ -726,8 +726,18 @@ retry_snap:
ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,
&iocb->ki_pos);
} else {
- ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+ /*
+ * buffered write; drop Fw early to avoid slow
+ * revocation if we get stuck on balance_dirty_pages
+ */
+ int dirty;
+
+ spin_lock(&inode->i_lock);
+ dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
+ spin_unlock(&inode->i_lock);
+ ceph_put_cap_refs(ci, got);
+ ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
if ((ret >= 0 || ret == -EIOCBQUEUED) &&
((file->f_flags & O_SYNC) || IS_SYNC(file->f_mapping->host)
|| ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL))) {
@@ -735,7 +745,12 @@ retry_snap:
if (err < 0)
ret = err;
}
+
+ if (dirty)
+ __mark_inode_dirty(inode, dirty);
+ goto out;
}
+
if (ret >= 0) {
int dirty;
spin_lock(&inode->i_lock);
@@ -745,12 +760,13 @@ retry_snap:
__mark_inode_dirty(inode, dirty);
}
-out:
+out_put:
dout("aio_write %p %llx.%llx %llu~%u dropping cap refs on %s\n",
inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
ceph_cap_string(got));
ceph_put_cap_refs(ci, got);
+out:
if (ret == -EOLDSNAPC) {
dout("aio_write %p %llx.%llx %llu~%u got EOLDSNAPC, retrying\n",
inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len);