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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>
This commit is contained in:
Sage Weil 2011-07-26 11:27:34 -07:00
parent 4cf9d54463
commit d8de9ab63a
1 changed files with 19 additions and 3 deletions
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22
fs/ceph/file.c
View File

@ -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);