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 I'll be posting a RFC patch for actual problem next week. > 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/ -- Mateusz Guzik -- 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
