From efab0b5d3eed6aa71f8e3233e4e11774eedc04dc Mon Sep 17 00:00:00 2001 From: Andres Salomon Date: Wed, 11 Feb 2009 13:27:02 -0800 Subject: [JFFS2] force the jffs2 GC daemon to behave a bit better I've noticed some pretty poor behavior on OLPC machines after bootup, when gdm/X are starting. The GCD monopolizes the scheduler (which in turns means it gets to do more nand i/o), which results in processes taking much much longer than they should to start. As an example, on an OLPC machine going from OFW to a usable X (via auto-login gdm) takes 2m 30s. The majority of this time is consumed by the switch into graphical mode. With this patch, we cut a full 60s off of bootup time. After bootup, things are much snappier as well. Note that we have seen a CRC node error with this patch that causes the machine to fail to boot, but we've also seen that problem without this patch. Signed-off-by: Andres Salomon Signed-off-by: Andrew Morton Signed-off-by: David Woodhouse --- fs/jffs2/background.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) (limited to 'fs') diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index 3cceef4ad2b7..e9580104b6ba 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -95,13 +95,17 @@ static int jffs2_garbage_collect_thread(void *_c) spin_unlock(&c->erase_completion_lock); - /* This thread is purely an optimisation. But if it runs when - other things could be running, it actually makes things a - lot worse. Use yield() and put it at the back of the runqueue - every time. Especially during boot, pulling an inode in - with read_inode() is much preferable to having the GC thread - get there first. */ - yield(); + /* Problem - immediately after bootup, the GCD spends a lot + * of time in places like jffs2_kill_fragtree(); so much so + * that userspace processes (like gdm and X) are starved + * despite plenty of cond_resched()s and renicing. Yield() + * doesn't help, either (presumably because userspace and GCD + * are generally competing for a higher latency resource - + * disk). + * This forces the GCD to slow the hell down. Pulling an + * inode in with read_inode() is much preferable to having + * the GC thread get there first. */ + schedule_timeout_interruptible(msecs_to_jiffies(50)); /* Put_super will send a SIGKILL and then wait on the sem. */ -- cgit v1.2.2 From 4c41bd0ec953954158f92bed5d3062645062b98e Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 16 Feb 2009 21:29:31 +0100 Subject: [JFFS2] fix mount crash caused by removed nodes At scan time we observed following scenario: node A inserted node B inserted node C inserted -> sets overlapped flag on node B node A is removed due to CRC failure -> overlapped flag on node B remains while (tn->overlapped) tn = tn_prev(tn); ==> crash, when tn_prev(B) is referenced. When the ultimate node is removed at scan time and the overlapped flag is set on the penultimate node, then nothing updates the overlapped flag of that node. The overlapped iterators blindly expect that the ultimate node does not have the overlapped flag set, which causes the scan code to crash. It would be a huge overhead to go through the node chain on node removal and fix up the overlapped flags, so detecting such a case on the fly in the overlapped iterators is a simpler and reliable solution. Cc: stable@kernel.org Signed-off-by: Thomas Gleixner Signed-off-by: David Woodhouse --- fs/jffs2/readinode.c | 42 +++++++++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 9 deletions(-) (limited to 'fs') diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c index 6ca08ad887c0..1fc1e92356ee 100644 --- a/fs/jffs2/readinode.c +++ b/fs/jffs2/readinode.c @@ -220,7 +220,7 @@ static int jffs2_add_tn_to_tree(struct jffs2_sb_info *c, struct jffs2_tmp_dnode_info *tn) { uint32_t fn_end = tn->fn->ofs + tn->fn->size; - struct jffs2_tmp_dnode_info *this; + struct jffs2_tmp_dnode_info *this, *ptn; dbg_readinode("insert fragment %#04x-%#04x, ver %u at %08x\n", tn->fn->ofs, fn_end, tn->version, ref_offset(tn->fn->raw)); @@ -251,11 +251,18 @@ static int jffs2_add_tn_to_tree(struct jffs2_sb_info *c, if (this) { /* If the node is coincident with another at a lower address, back up until the other node is found. It may be relevant */ - while (this->overlapped) - this = tn_prev(this); - - /* First node should never be marked overlapped */ - BUG_ON(!this); + while (this->overlapped) { + ptn = tn_prev(this); + if (!ptn) { + /* + * We killed a node which set the overlapped + * flags during the scan. Fix it up. + */ + this->overlapped = 0; + break; + } + this = ptn; + } dbg_readinode("'this' found %#04x-%#04x (%s)\n", this->fn->ofs, this->fn->ofs + this->fn->size, this->fn ? "data" : "hole"); } @@ -360,7 +367,17 @@ static int jffs2_add_tn_to_tree(struct jffs2_sb_info *c, } if (!this->overlapped) break; - this = tn_prev(this); + + ptn = tn_prev(this); + if (!ptn) { + /* + * We killed a node which set the overlapped + * flags during the scan. Fix it up. + */ + this->overlapped = 0; + break; + } + this = ptn; } } @@ -456,8 +473,15 @@ static int jffs2_build_inode_fragtree(struct jffs2_sb_info *c, eat_last(&rii->tn_root, &last->rb); ver_insert(&ver_root, last); - if (unlikely(last->overlapped)) - continue; + if (unlikely(last->overlapped)) { + if (pen) + continue; + /* + * We killed a node which set the overlapped + * flags during the scan. Fix it up. + */ + last->overlapped = 0; + } /* Now we have a bunch of nodes in reverse version order, in the tree at ver_root. Most of the time, -- cgit v1.2.2