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-rw-r--r--Documentation/filesystems/ceph.txt16
1 files changed, 16 insertions, 0 deletions
diff --git a/Documentation/filesystems/ceph.txt b/Documentation/filesystems/ceph.txt
index 0b302a11718a..d7f011ddc150 100644
--- a/Documentation/filesystems/ceph.txt
+++ b/Documentation/filesystems/ceph.txt
@@ -62,6 +62,18 @@ subdirectories, and a summation of all nested file sizes. This makes
the identification of large disk space consumers relatively quick, as
no 'du' or similar recursive scan of the file system is required.
+Finally, Ceph also allows quotas to be set on any directory in the system.
+The quota can restrict the number of bytes or the number of files stored
+beneath that point in the directory hierarchy. Quotas can be set using
+extended attributes 'ceph.quota.max_files' and 'ceph.quota.max_bytes', eg:
+
+ setfattr -n ceph.quota.max_bytes -v 100000000 /some/dir
+ getfattr -n ceph.quota.max_bytes /some/dir
+
+A limitation of the current quotas implementation is that it relies on the
+cooperation of the client mounting the file system to stop writers when a
+limit is reached. A modified or adversarial client cannot be prevented
+from writing as much data as it needs.
Mount Syntax
============
@@ -137,6 +149,10 @@ Mount Options
noasyncreaddir
Do not use the dcache as above for readdir.
+ noquotadf
+ Report overall filesystem usage in statfs instead of using the root
+ directory quota.
+
More Information
================