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Here's a patch to the fcntl.2 manpage that explains the working of F_GETLEASE in a bit more detail during lease breaks. Basically, what happens is this: When a lease break is initiated by a lease breaker, subsequent F_GETLEASE calls return the target lease type after the lease break and not the existing lease type. This behavior persists until the lease holder downgrades/unlocks the lease or the kernel forcibly does it after the lease break timeout expires.

The implicit assumption is that F_GETLEASE should return the existing lock type until the downgrade/unlock has actually taken place, which is not true. I've verified that the kernel indeed returns the target lease type. It is also simple enough to verify this behavior in a small program, where you can observe that the lease type returned by F_GETLEASE in the signal handler for a lease break is different from the existing lease type.

Signed-off-by: Abhi Das <adas@xxxxxxxxxx>

diff --git a/man2/fcntl.2 b/man2/fcntl.2
index b2a985a..5256dc6 100644
--- a/man2/fcntl.2
+++ b/man2/fcntl.2
@@ -865,6 +865,16 @@ the number of seconds specified in
 .I /proc/sys/fs/lease-break-time
 then the kernel forcibly removes or downgrades the lease holder's lease.
+Once a lease break has been initiated,
+returns the target lease type (either 
+depending on what would be compatible with the lease breaker) until the 
+lease holder voluntarily downgrades or removes the lease or the kernel 
+forcibly does so after the lease break timer expires.
 Once the lease has been voluntarily or forcibly removed or downgraded,
 and assuming the lease breaker has not unblocked its system call,
 the kernel permits the lease breaker's system call to proceed.
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