file locking

FUSE-Mount.md

@@ -13,8 +13,23 @@ With "weed mount", the files can be operated as a local file. The following oper
 * display free disk space
 * copy file range
 * lseek
+* advisory file locking (`flock(2)` and POSIX `fcntl(2)` byte-range locks)
 * extended attributes (xattr)
 
+### Advisory File Locking
+
+SeaweedFS supports advisory file locking over FUSE:
+
+* whole-file locks via `flock(2)`
+* POSIX byte-range locks via `fcntl(2)` (`F_SETLK`, `F_SETLKW`, `F_GETLK`)
+
+The locks follow normal close semantics:
+
+* POSIX `fcntl` locks are released when the closing lock owner closes the file
+* `flock` locks are released with the file description close path
+
+These are advisory locks, so applications must cooperate by taking and honoring them.
+
 ### Extended Attributes (xattr)
 
 SeaweedFS supports POSIX extended attributes on files and directories via FUSE mount. You can use standard tools like `setfattr`, `getfattr`, and `xattr` to manage custom metadata.
@@ -365,4 +380,4 @@ From https://github.com/seaweedfs/seaweedfs/issues/877
 Workaround is to use Linux capabilities on weed executable.
 setcap cap_net_raw,cap_net_admin,cap_dac_override+eip /usr/local/bin/weed
 After that you need to use "weed mount" with option allowOthers=false  
-```
+```