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* d_type and bind mounts
@ 2019-02-11 19:59 Tavian Barnes
  2019-02-11 20:59 ` Dave Chinner
  0 siblings, 1 reply; 2+ messages in thread
From: Tavian Barnes @ 2019-02-11 19:59 UTC (permalink / raw)
  To: linux-fsdevel, linux-kernel

It seems that readdir()/getdents() fill d_type from the underlying
filesystem, not respecting bind mounts of non-directories:

$ touch mount_point
$ sudo mount --bind /dev/null mount_point
$ find -name mount_point -type c
$ find -name mount_point -type f
./mount_point

(Requires a fairly recent GNU findutils to reproduce, older ones
always call stat().)  I've seen similar discussions about d_ino being
for the underlying file, not the mount point, which people have said
is technically a POSIX violation but also unlikely to be fixed.  Is
the same true of d_type?  And is there some workaround a program could
use to get the actual type without the overhead of a whole stat()
call?  For example, a way to tell whether a directory entry is a mount
point?

For reference, the relevant findutils bug is
https://savannah.gnu.org/bugs/?54913.

(Please keep me cc'd, I'm not subscribed to lkml or fsdevel.  Thanks!)

-- 
Tavian Barnes

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2019-02-11 19:59 d_type and bind mounts Tavian Barnes
2019-02-11 20:59 ` Dave Chinner

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