If sendfile() is called with a zero count, it will nevertheless
try to send the data. This is mostly meaningless, it causes
waste of resources, and in some cases delays.
This commit adds special handling for this case, allowing
sendfile to return immediately zero. The new behavior is
in line with the Linux variant of sendfile.
Squashed commit of the following:
sched/sched/sched_getsockets.c: Fix an error in conditional compilation.
fs/: Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
Documentation/: Remove all references to CONFIG_NSOCKET_DESCRIPTORS == 0
include/: Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
libs/: Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
net/: Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
sched/: Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
syscall/: Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
tools/: Fixups for CONFIG_NSOCKET_DESCRIPTORS no longer used to disable sockets.
Squashed commit of the following:
configs/: The few configurations that formerly set CONFIG_NFILE_DESCRIPTORS=0 should not default, rather they should set the number of descriptors to 3.
fs/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
tools/: Tools updates for changes to usage of CONFIG_NFILE_DESCRIPTORS.
syscall/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
libs/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
include/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
drivers/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
Documentation/: Remove all references to CONFIG_NFILE_DESCRIPTORS == 0
binfmt/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
arch/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
net/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
sched/: Remove all conditional logic based on CONFIG_NFILE_DESCRIPTORS == 0
sched/Kconfig: CONFIG_NFILE_DESCRIPTORS may no longer to set to a value less than 3
configs/: Remove all settings for CONFIG_NFILE_DESCRIPTORS < 3
