* INFORMATIONAL ONLY - NO ACTION/READING NEEDED
BUG: https://bugs.linaro.org/show_bug.cgi?id=3881
Because the lack of the following commit:
commit 764baba80168ad3adafb521d2ab483ccbc49e344 Author: Amir Goldstein amir73il@gmail.com Date: Sun Feb 4 15:35:09 2018 +0200
ovl: hash non-dir by lower inode for fsnotify
INFO: inotify issue with non-dir non-upper files in overlayfs exists in LTS <= v4.14. INFO: LTP inotify08 test fails on * v4.14 and bellow * and should be skipped.
Trying to cherry-pick to v4.14 has proven not to be feasible without bringing many new features/code into LTS tree (up to any Linux distribution to decide to backport or not).
For clean cherry picks, commits:
ovl: hash non-dir by lower inode for fsnotify ovl: hash non-indexed dir by upper inode for NFS export ovl: do not pass overlay dentry to ovl_get_inode() ovl: hash directory inodes for fsnotify ovl: no direct iteration for dir with origin xattr Revert "ovl: hash directory inodes for fsnotify"
are needed AND all the logic for setting up "origin" variable in ovl_lookup, passed to ovl_lookup_index() after it got its prototype changed, would still be missing. Unfortunately the "origin" also depends on commit 051224438 ("ovl: generalize ovl_verify_origin() and helpers") and some others ones that refactor many functions.
-Rafael
On Mon, Mar 12, 2018 at 12:02 PM gregkh@linuxfoundation.org wrote:
The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 764baba80168ad3adafb521d2ab483ccbc49e344 Mon Sep 17 00:00:00 2001 From: Amir Goldstein amir73il@gmail.com Date: Sun, 4 Feb 2018 15:35:09 +0200 Subject: [PATCH] ovl: hash non-dir by lower inode for fsnotify
Commit 31747eda41ef ("ovl: hash directory inodes for fsnotify") fixed an issue of inotify watch on directory that stops getting events after dropping dentry caches.
A similar issue exists for non-dir non-upper files, for example:
$ mkdir -p lower upper work merged $ touch lower/foo $ mount -t overlay -o lowerdir=lower,workdir=work,upperdir=upper none merged $ inotifywait merged/foo & $ echo 2 > /proc/sys/vm/drop_caches $ cat merged/foo
inotifywait doesn't get the OPEN event, because ovl_lookup() called from 'cat' allocates a new overlay inode and does not reuse the watched inode.
Fix this by hashing non-dir overlay inodes by lower real inode in the following cases that were not hashed before this change:
- A non-upper overlay mount
- A lower non-hardlink when index=off
A helper ovl_hash_bylower() was added to put all the logic and documentation about which real inode an overlay inode is hashed by into one place.
The issue dates back to initial version of overlayfs, but this patch depends on ovl_inode code that was introduced in kernel v4.13.
Cc: stable@vger.kernel.org #v4.13 Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index fcd97b783fa1..3b1bd469accd 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -669,38 +669,59 @@ struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real, return inode; }
+/*
- Does overlay inode need to be hashed by lower inode?
- */
+static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
struct dentry *lower, struct dentry *index)+{
struct ovl_fs *ofs = sb->s_fs_info;/* No, if pure upper */if (!lower)return false;/* Yes, if already indexed */if (index)return true;/* Yes, if won't be copied up */if (!ofs->upper_mnt)return true;/* No, if lower hardlink is or will be broken on copy up */if ((upper || !ovl_indexdir(sb)) &&!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)return false;/* No, if non-indexed upper with NFS export */if (sb->s_export_op && upper)return false;/* Otherwise, hash by lower inode for fsnotify */return true;+}
struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry, struct dentry *lowerdentry, struct dentry *index, unsigned int numlower) {
struct ovl_fs *ofs = sb->s_fs_info; struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL; struct inode *inode;/* Already indexed or could be indexed on copy up? */bool indexed = (index || (ovl_indexdir(sb) && !upperdentry));struct dentry *origin = indexed ? lowerdentry : NULL;
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index); bool is_dir;
if (WARN_ON(upperdentry && indexed && !lowerdentry))return ERR_PTR(-EIO);if (!realinode) realinode = d_inode(lowerdentry); /** Copy up origin (lower) may exist for non-indexed non-dir upper, but* we must not use lower as hash key in that case.* Hash non-dir that is or could be indexed by origin inode.* Hash dir that is or could be merged by origin inode.* Hash pure upper and non-indexed non-dir by upper inode.* Hash non-indexed dir by upper inode for NFS export.
* Copy up origin (lower) may exist for non-indexed upper, but we must* not use lower as hash key if this is a broken hardlink. */ is_dir = S_ISDIR(realinode->i_mode);
if (is_dir && (indexed || !sb->s_export_op || !ofs->upper_mnt))origin = lowerdentry;if (upperdentry || origin) {struct inode *key = d_inode(origin ?: upperdentry);
if (upperdentry || bylower) {struct inode *key = d_inode(bylower ? lowerdentry :upperdentry); unsigned int nlink = is_dir ? 1 : realinode->i_nlink; inode = iget5_locked(sb, (unsigned long) key,@@ -728,6 +749,7 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry, nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink); set_nlink(inode, nlink); } else {
/* Lower hardlink that will be broken on copy up */ inode = new_inode(sb); if (!inode) goto out_nomem;