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GFS2: Check rs_free with rd_rsspin protection 

For the last process to close a file opened for write, function
gfs2_rsqa_delete was deleting the file's inode's block reservation
out of the rgrp reservations tree. Then it was checking to make sure
rs_free was 0, but it was performing the check outside the protection
of rd_rsspin spin_lock. The rd_rsspin spin_lock protection is needed
to prevent a race between the process freeing the reservation and
another who is allocating a new set of blocks inside the same rgrp
for the same inode, thus changing its value.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
This commit is contained in:
Bob Peterson 2016-07-06 10:36:43 -05:00
parent fd4c5748b8
commit 44f52122a2
1 changed files with 2 additions and 3 deletions
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5
fs/gfs2/rgrp.c
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@ -658,6 +658,7 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
if (rgd) {
spin_lock(&rgd->rd_rsspin);
__rs_deltree(rs);
BUG_ON(rs->rs_free);
spin_unlock(&rgd->rd_rsspin);
}
}
@ -671,10 +672,8 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
void gfs2_rsqa_delete(struct gfs2_inode *ip, atomic_t *wcount)
{
down_write(&ip->i_rw_mutex);
if ((wcount == NULL) || (atomic_read(wcount) <= 1)) {
if ((wcount == NULL) || (atomic_read(wcount) <= 1))
gfs2_rs_deltree(&ip->i_res);
BUG_ON(ip->i_res.rs_free);
}
up_write(&ip->i_rw_mutex);
gfs2_qa_delete(ip, wcount);
}