On Thu, 18 Sep 2014 13:22:07 +0200 Mateusz Guzik wrote: > On Thu, Sep 18, 2014 at 02:55:00PM +0400, Mikhail Efremov wrote: > > Only exchange source and destination filenames > > if flags contain RENAME_EXCHANGE. > > But names are still exchanged without RENAME_EXCHANGE, provided they are > long enough. > > da1ce0670c14 introduced this behaviour also for short names and this is > what you are reverting here. > > That said, I think the patch is fine as an interim change, but should > note facts mentioned above. > > For more info please see https://lkml.org/lkml/2014/9/7/6 Thanks for pointing out that thread to me, I didn't read it before sending the patch. > I'll be posting a RFC patch for actual problem next week. I suppose then that no sense to resend this patch right now, I'll just wait the proper solution from you. Yet this patch can be used as a temporary workaround (as you mentioned above) if the proper solution takes longer than expected to implement. > > In case if executable file was running and replaced by > > other file /proc/PID/exe should still show correct file name, > > not the old name of the file by which it was replaced. > > > > > > The scenario when this bug manifests itself was like this: > > * ALT Linux uses rpm and start-stop-daemon; > > * during a package upgrade rpm creates a temporary file > > for an executable to rename it upon successful unpacking; > > * start-stop-daemon is run subsequently and it obtains > > the (nonexistant) temporary filename via /proc/PID/exe > > thus failing to identify the running process. > > > > Cc: Miklos Szeredi <mszeredi@xxxxxxx> > > Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> > > Cc: linux-fsdevel@xxxxxxxxxxxxxxx > > > > Fixes: da1ce0670c14 "vfs: add cross-rename" > > Signed-off-by: Mikhail Efremov <sem@xxxxxxxxxxxx> > > --- > > fs/dcache.c | 27 +++++++++++++++++++-------- > > 1 file changed, 19 insertions(+), 8 deletions(-) > > > > diff --git a/fs/dcache.c b/fs/dcache.c > > index 7a5b514..3218570 100644 > > --- a/fs/dcache.c > > +++ b/fs/dcache.c > > @@ -2372,7 +2372,8 @@ void dentry_update_name_case(struct dentry *dentry, struct qstr *name) > > } > > EXPORT_SYMBOL(dentry_update_name_case); > > > > -static void switch_names(struct dentry *dentry, struct dentry *target) > > +static void switch_names(struct dentry *dentry, struct dentry *target, > > + bool exchange) > > { > > if (dname_external(target)) { > > if (dname_external(dentry)) { > > @@ -2404,11 +2405,21 @@ static void switch_names(struct dentry *dentry, struct dentry *target) > > /* > > * Both are internal. > > */ > > - unsigned int i; > > - BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); > > - for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { > > - swap(((long *) &dentry->d_iname)[i], > > - ((long *) &target->d_iname)[i]); > > + if (exchange) { > > + unsigned int i; > > + > > + BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, > > + sizeof(long))); > > + for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); > > + i++) { > > + swap(((long *) &dentry->d_iname)[i], > > + ((long *) &target->d_iname)[i]); > > + } > > + } else { > > + memcpy(dentry->d_iname, target->d_name.name, > > + target->d_name.len + 1); > > + dentry->d_name.len = target->d_name.len; > > + return; > > } > > } > > } > > @@ -2510,7 +2521,7 @@ static void __d_move(struct dentry *dentry, struct dentry *target, > > list_del(&target->d_u.d_child); > > > > /* Switch the names.. */ > > - switch_names(dentry, target); > > + switch_names(dentry, target, exchange); > > swap(dentry->d_name.hash, target->d_name.hash); > > > > /* ... and switch the parents */ > > @@ -2649,7 +2660,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) > > > > dparent = dentry->d_parent; > > > > - switch_names(dentry, anon); > > + switch_names(dentry, anon, false); > > swap(dentry->d_name.hash, anon->d_name.hash); > > > > dentry->d_parent = dentry; > > -- > > 1.8.5.5 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > -- WBR, Mikhail Efremov -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
