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authorLinus Torvalds <torvalds@linux-foundation.org>2019-06-06 12:31:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-06-06 12:31:15 -0700
commit5d6b501fe5421c5df662e2935f55f5e3d2b5e012 (patch)
treeb585152e88b791047ca679eacdd958b70674cf7b /Documentation
parent211758573b01f4cd27308464573d112ef85e0e1a (diff)
parent5d3211b651a012bc77410ebf097b7271a7ce5c95 (diff)
downloadlinux-5d6b501fe5421c5df662e2935f55f5e3d2b5e012.tar.bz2
Merge tag 'ovl-fixes-5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs fixes from Miklos Szeredi: "Here's one fix for a class of bugs triggered by syzcaller, and one that makes xfstests fail less" * tag 'ovl-fixes-5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: doc: add non-standard corner cases ovl: detect overlapping layers ovl: support the FS_IOC_FS[SG]ETXATTR ioctls
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/overlayfs.txt16
1 files changed, 14 insertions, 2 deletions
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
index eef7d9d259e8..1da2f1668f08 100644
--- a/Documentation/filesystems/overlayfs.txt
+++ b/Documentation/filesystems/overlayfs.txt
@@ -336,8 +336,20 @@ the copied layers will fail the verification of the lower root file handle.
Non-standard behavior
---------------------
-Overlayfs can now act as a POSIX compliant filesystem with the following
-features turned on:
+Current version of overlayfs can act as a mostly POSIX compliant
+filesystem.
+
+This is the list of cases that overlayfs doesn't currently handle:
+
+a) POSIX mandates updating st_atime for reads. This is currently not
+done in the case when the file resides on a lower layer.
+
+b) If a file residing on a lower layer is opened for read-only and then
+memory mapped with MAP_SHARED, then subsequent changes to the file are not
+reflected in the memory mapping.
+
+The following options allow overlayfs to act more like a standards
+compliant filesystem:
1) "redirect_dir"