This is a note to let you know that I've just added the patch titled gfs2: Move the inode glock locking to gfs2_file_buffered_write to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: gfs2-move-the-inode-glock-locking-to-gfs2_file_buffered_write.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Fri Apr 29 11:07:48 AM CEST 2022 From: Anand Jain <anand.jain@xxxxxxxxxx> Date: Fri, 15 Apr 2022 06:28:45 +0800 Subject: gfs2: Move the inode glock locking to gfs2_file_buffered_write To: stable@xxxxxxxxxxxxxxx Cc: linux-btrfs@xxxxxxxxxxxxxxx, Andreas Gruenbacher <agruenba@xxxxxxxxxx>, Anand Jain <anand.jain@xxxxxxxxxx> Message-ID: <cc3db66fcbea7329e3cc7246cd329b719f76f323.1649951733.git.anand.jain@xxxxxxxxxx> From: Andreas Gruenbacher <agruenba@xxxxxxxxxx> commit b924bdab7445946e2ed364a0e6e249d36f1f1158 upstream So far, for buffered writes, we were taking the inode glock in gfs2_iomap_begin and dropping it in gfs2_iomap_end with the intention of not holding the inode glock while iomap_write_actor faults in user pages. It turns out that iomap_write_actor is called inside iomap_begin ... iomap_end, so the user pages were still faulted in while holding the inode glock and the locking code in iomap_begin / iomap_end was completely pointless. Move the locking into gfs2_file_buffered_write instead. We'll take care of the potential deadlocks due to faulting in user pages while holding a glock in a subsequent patch. Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/gfs2/bmap.c | 60 --------------------------------------------------------- fs/gfs2/file.c | 27 +++++++++++++++++++++++++ 2 files changed, 28 insertions(+), 59 deletions(-) --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -961,46 +961,6 @@ hole_found: goto out; } -static int gfs2_write_lock(struct inode *inode) -{ - struct gfs2_inode *ip = GFS2_I(inode); - struct gfs2_sbd *sdp = GFS2_SB(inode); - int error; - - gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh); - error = gfs2_glock_nq(&ip->i_gh); - if (error) - goto out_uninit; - if (&ip->i_inode == sdp->sd_rindex) { - struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode); - - error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE, - GL_NOCACHE, &m_ip->i_gh); - if (error) - goto out_unlock; - } - return 0; - -out_unlock: - gfs2_glock_dq(&ip->i_gh); -out_uninit: - gfs2_holder_uninit(&ip->i_gh); - return error; -} - -static void gfs2_write_unlock(struct inode *inode) -{ - struct gfs2_inode *ip = GFS2_I(inode); - struct gfs2_sbd *sdp = GFS2_SB(inode); - - if (&ip->i_inode == sdp->sd_rindex) { - struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode); - - gfs2_glock_dq_uninit(&m_ip->i_gh); - } - gfs2_glock_dq_uninit(&ip->i_gh); -} - static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos, unsigned len) { @@ -1118,11 +1078,6 @@ out_qunlock: return ret; } -static inline bool gfs2_iomap_need_write_lock(unsigned flags) -{ - return (flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT); -} - static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, unsigned flags, struct iomap *iomap, struct iomap *srcmap) @@ -1135,12 +1090,6 @@ static int gfs2_iomap_begin(struct inode iomap->flags |= IOMAP_F_BUFFER_HEAD; trace_gfs2_iomap_start(ip, pos, length, flags); - if (gfs2_iomap_need_write_lock(flags)) { - ret = gfs2_write_lock(inode); - if (ret) - goto out; - } - ret = __gfs2_iomap_get(inode, pos, length, flags, iomap, &mp); if (ret) goto out_unlock; @@ -1168,10 +1117,7 @@ static int gfs2_iomap_begin(struct inode ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap, &mp); out_unlock: - if (ret && gfs2_iomap_need_write_lock(flags)) - gfs2_write_unlock(inode); release_metapath(&mp); -out: trace_gfs2_iomap_end(ip, iomap, ret); return ret; } @@ -1219,15 +1165,11 @@ static int gfs2_iomap_end(struct inode * } if (unlikely(!written)) - goto out_unlock; + return 0; if (iomap->flags & IOMAP_F_SIZE_CHANGED) mark_inode_dirty(inode); set_bit(GLF_DIRTY, &ip->i_gl->gl_flags); - -out_unlock: - if (gfs2_iomap_need_write_lock(flags)) - gfs2_write_unlock(inode); return 0; } --- a/fs/gfs2/file.c +++ b/fs/gfs2/file.c @@ -881,13 +881,40 @@ static ssize_t gfs2_file_buffered_write( { struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); + struct gfs2_inode *ip = GFS2_I(inode); + struct gfs2_sbd *sdp = GFS2_SB(inode); ssize_t ret; + gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh); + ret = gfs2_glock_nq(&ip->i_gh); + if (ret) + goto out_uninit; + + if (inode == sdp->sd_rindex) { + struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode); + + ret = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE, + GL_NOCACHE, &m_ip->i_gh); + if (ret) + goto out_unlock; + } + current->backing_dev_info = inode_to_bdi(inode); ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops); current->backing_dev_info = NULL; if (ret > 0) iocb->ki_pos += ret; + + if (inode == sdp->sd_rindex) { + struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode); + + gfs2_glock_dq_uninit(&m_ip->i_gh); + } + +out_unlock: + gfs2_glock_dq(&ip->i_gh); +out_uninit: + gfs2_holder_uninit(&ip->i_gh); return ret; } Patches currently in stable-queue which might be from anand.jain@xxxxxxxxxx are queue-5.15/gup-turn-fault_in_pages_-readable-writeable-into-fault_in_-readable-writeable.patch queue-5.15/iov_iter-introduce-nofault-flag-to-disable-page-faults.patch queue-5.15/gfs2-fix-mmap-page-fault-deadlocks-for-direct-i-o.patch queue-5.15/iomap-support-partial-direct-i-o-on-user-copy-failures.patch queue-5.15/mm-gup-make-fault_in_safe_writeable-use-fixup_user_fault.patch queue-5.15/gfs2-add-wrapper-for-iomap_file_buffered_write.patch queue-5.15/gup-introduce-foll_nofault-flag-to-disable-page-faults.patch queue-5.15/iov_iter-introduce-fault_in_iov_iter_writeable.patch queue-5.15/gfs2-fix-mmap-page-fault-deadlocks-for-buffered-i-o.patch queue-5.15/btrfs-fallback-to-blocking-mode-when-doing-async-dio-over-multiple-extents.patch queue-5.15/gfs2-clean-up-function-may_grant.patch queue-5.15/btrfs-fix-deadlock-due-to-page-faults-during-direct-io-reads-and-writes.patch queue-5.15/iov_iter-turn-iov_iter_fault_in_readable-into-fault_in_iov_iter_readable.patch queue-5.15/gfs2-move-the-inode-glock-locking-to-gfs2_file_buffered_write.patch queue-5.15/gfs2-introduce-flag-for-glock-holder-auto-demotion.patch queue-5.15/iomap-fix-iomap_dio_rw-return-value-for-user-copies.patch queue-5.15/gfs2-eliminate-ip-i_gh.patch queue-5.15/iomap-add-done_before-argument-to-iomap_dio_rw.patch