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author | J. Bruce Fields <bfields@fieldses.org> | 2006-11-14 20:51:40 (GMT) |
---|---|---|
committer | J. Bruce Fields <bfields@citi.umich.edu> | 2007-07-18 23:14:47 (GMT) |
commit | f9ffed26d6f3e6ac9988947242821579d615fda7 (patch) | |
tree | f7dc037b9b1a90511751532be5ebc47c820ed407 | |
parent | a9933cea7a1d80dd9efae9f1acd857f5dce742b9 (diff) | |
download | linux-f9ffed26d6f3e6ac9988947242821579d615fda7.tar.xz |
locks: provide a file lease method enabling cluster-coherent leases
Currently leases are only kept locally, so there's no way for a distributed
filesystem to enforce them against multiple clients. We're particularly
interested in the case of nfsd exporting a cluster filesystem, in which
case nfsd needs cluster-coherent leases in order to implement delegations
correctly.
Also add some documentation.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
-rw-r--r-- | fs/locks.c | 24 | ||||
-rw-r--r-- | include/linux/fs.h | 1 |
2 files changed, 23 insertions, 2 deletions
@@ -1429,7 +1429,24 @@ out: * @lease: file_lock to use * * Call this to establish a lease on the file. - * The fl_lmops fl_break function is required by break_lease + * The (*lease)->fl_lmops->fl_break operation must be set; if not, + * break_lease will oops! + * + * This will call the filesystem's setlease file method, if + * defined. Note that there is no getlease method; instead, the + * filesystem setlease method should call back to setlease() to + * add a lease to the inode's lease list, where fcntl_getlease() can + * find it. Since fcntl_getlease() only reports whether the current + * task holds a lease, a cluster filesystem need only do this for + * leases held by processes on this node. + * + * There is also no break_lease method; filesystems that + * handle their own leases shoud break leases themselves from the + * filesystem's open, create, and (on truncate) setattr methods. + * + * Warning: the only current setlease methods exist only to disable + * leases in certain cases. More vfs changes may be required to + * allow a full filesystem lease implementation. */ int vfs_setlease(struct file *filp, long arg, struct file_lock **lease) @@ -1437,7 +1454,10 @@ int vfs_setlease(struct file *filp, long arg, struct file_lock **lease) int error; lock_kernel(); - error = setlease(filp, arg, lease); + if (filp->f_op && filp->f_op->setlease) + error = filp->f_op->setlease(filp, arg, lease); + else + error = setlease(filp, arg, lease); unlock_kernel(); return error; diff --git a/include/linux/fs.h b/include/linux/fs.h index a24f029..c8ddf34 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1122,6 +1122,7 @@ struct file_operations { int (*flock) (struct file *, int, struct file_lock *); ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); + int (*setlease)(struct file *, long, struct file_lock **); }; struct inode_operations { |