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authorMiklos Szeredi <mszeredi@redhat.com>2016-09-01 11:11:59 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2016-09-01 11:11:59 +0200
commit2a3a2a3f35249412e35fbb48b743348c40373409 (patch)
tree4615559df3c1faddf9ef388adce449fb8e89f680 /include
parent5201dc449e4b6b6d7e92f7f974269b11681f98b5 (diff)
ovl: don't cache acl on overlay layer
Some operations (setxattr/chmod) can make the cached acl stale. We either need to clear overlay's acl cache for the affected inode or prevent acl caching on the overlay altogether. Preventing caching has the following advantages: - no double caching, less memory used - overlay cache doesn't go stale when fs clears it's own cache Possible disadvantage is performance loss. If that becomes a problem get_acl() can be optimized for overlayfs. This patch disables caching by pre setting i_*acl to a value that - has bit 0 set, so is_uncached_acl() will return true - is not equal to ACL_NOT_CACHED, so get_acl() will not overwrite it The constant -3 was chosen for this purpose. Fixes: 39a25b2b3762 ("ovl: define ->get_acl() for overlay inodes") Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/fs.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3523bf62f328..901e25d495cc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -574,6 +574,7 @@ static inline void mapping_allow_writable(struct address_space *mapping)
struct posix_acl;
#define ACL_NOT_CACHED ((void *)(-1))
+#define ACL_DONT_CACHE ((void *)(-3))
static inline struct posix_acl *
uncached_acl_sentinel(struct task_struct *task)