From c412a97cf6c5253fcf4ae5545be5775b2417d61b Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Mon, 22 Aug 2022 11:30:12 -0500 Subject: [PATCH] gfs2: Use TRY lock in gfs2_inode_lookup for UNLINKED inodes Before this patch, delete_work_func() would check for the GLF_DEMOTE flag on the iopen glock and if set, it would perform special processing. However, there was a race whereby the GLF_DEMOTE flag could be set by another process after the check. Then when it called gfs2_lookup_by_inum() which calls gfs2_inode_lookup(), it tried to lock the iopen glock in SH mode, but the GLF_DEMOTE flag prevented the request from being granted. But the iopen glock could never be demoted because that happens when the inode is evicted, and the evict was never completed because of the failed lookup. To fix that, change function gfs2_inode_lookup() so that when GFS2_BLKST_UNLINKED inodes are searched, it uses the LM_FLAG_TRY flag for the iopen glock. If the locking request fails, fail gfs2_inode_lookup() with -EAGAIN so that delete_work_func() can retry the operation later. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher --- fs/gfs2/glock.c | 8 +++++--- fs/gfs2/inode.c | 10 ++++++++-- 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 41b6c89e4bf7..57dcfd05b362 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1018,16 +1018,18 @@ static void delete_work_func(struct work_struct *work) if (gfs2_queue_delete_work(gl, 5 * HZ)) return; } - goto out; } inode = gfs2_lookup_by_inum(sdp, no_addr, gl->gl_no_formal_ino, GFS2_BLKST_UNLINKED); - if (!IS_ERR_OR_NULL(inode)) { + if (IS_ERR(inode)) { + if (PTR_ERR(inode) == -EAGAIN && + (gfs2_queue_delete_work(gl, 5 * HZ))) + return; + } else { d_prune_aliases(inode); iput(inode); } -out: gfs2_glock_put(gl); } diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index c8ec876f33ea..56ded979988c 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -130,6 +130,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, if (inode->i_state & I_NEW) { struct gfs2_sbd *sdp = GFS2_SB(inode); struct gfs2_glock *io_gl; + int extra_flags = 0; error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl); @@ -141,9 +142,12 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, if (unlikely(error)) goto fail; - if (blktype != GFS2_BLKST_UNLINKED) + if (blktype == GFS2_BLKST_UNLINKED) + extra_flags |= LM_FLAG_TRY; + else gfs2_cancel_delete_work(io_gl); - error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, + error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, + GL_EXACT | extra_flags, &ip->i_iopen_gh); gfs2_glock_put(io_gl); if (unlikely(error)) @@ -210,6 +214,8 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, return inode; fail: + if (error == GLR_TRYFAILED) + error = -EAGAIN; if (gfs2_holder_initialized(&ip->i_iopen_gh)) gfs2_glock_dq_uninit(&ip->i_iopen_gh); if (gfs2_holder_initialized(&i_gh))