Messages in this thread Patch in this message | | | From | Yufen Yu <> | Subject | [PATCH] jffs2: remove fd from the f->dents list immediately. | Date | Fri, 16 Mar 2018 19:05:22 +0800 |
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commit 15953580e79b ("[JFFS2] Improve getdents vs. f_pos handling on NOR flash.") is introduced to resolve 'rm -r', which cannot remove all files: http://lists.infradead.org/pipermail/linux-mtd/2007-October/019658.html
However, it can cause the following issues:
1. 'deletion' dirents is alway in the f->dents list, wasting memory resource. For example: There is a file named 'file1'. Then we rename it: mv file1 file2; mv file2 file3; ... mv file99999 file1000000
When CONFIG_JFFS2_SUMMARY is not set, file1~file1000000 always in the f->dents list.
2. Since the list become longer and longer, more CPU time is used to traverse it.
After reverting the commit, we test 'rm -r', which can remove all files, and all seems OK!
Signed-off-by: Yufen Yu <yuyufen@huawei.com> --- fs/jffs2/write.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/fs/jffs2/write.c b/fs/jffs2/write.c index cda9a361368e..1deed35beb50 100644 --- a/fs/jffs2/write.c +++ b/fs/jffs2/write.c @@ -598,31 +598,32 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f, jffs2_add_fd_to_list(c, fd, &dir_f->dents); mutex_unlock(&dir_f->sem); } else { + struct jffs2_full_dirent **prev = &dir_f->dents; uint32_t nhash = full_name_hash(NULL, name, namelen); - fd = dir_f->dents; /* We don't actually want to reserve any space, but we do want to be holding the alloc_sem when we write to flash */ mutex_lock(&c->alloc_sem); mutex_lock(&dir_f->sem); - for (fd = dir_f->dents; fd; fd = fd->next) { - if (fd->nhash == nhash && - !memcmp(fd->name, name, namelen) && - !fd->name[namelen]) { - - jffs2_dbg(1, "Marking old dirent node (ino #%u) @%08x obsolete\n", - fd->ino, ref_offset(fd->raw)); - jffs2_mark_node_obsolete(c, fd->raw); - /* We don't want to remove it from the list immediately, - because that screws up getdents()/seek() semantics even - more than they're screwed already. Turn it into a - node-less deletion dirent instead -- a placeholder */ - fd->raw = NULL; - fd->ino = 0; - break; + while ((*prev) && (*prev)->nhash <= nhash) { + if ((*prev)->nhash == nhash && + !memcmp((*prev)->name, name, namelen) && + !(*prev)->name[namelen]) { + + struct jffs2_full_dirent *this = *prev; + + jffs2_dbg(1, "Marking old dirent node (ino #%u) @%08x obsolete\n", + this->ino, ref_offset(this->raw)); + *prev = this->next; + jffs2_mark_node_obsolete(c, this->raw); + jffs2_free_full_dirent(this); + + break; } + prev = &((*prev)->next); } + mutex_unlock(&dir_f->sem); } -- 2.13.6
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