Fix the discussion of the limitations on the dest_count and src_length
parameters to the fideduperange ioctl to reflect what's actually in the
kernel.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
man2/ioctl_fideduperange.2 | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/man2/ioctl_fideduperange.2 b/man2/ioctl_fideduperange.2
index 2112d10..057229d 100644
--- a/man2/ioctl_fideduperange.2
+++ b/man2/ioctl_fideduperange.2
@@ -95,7 +95,7 @@ struct file_dedupe_range_info {
.in
Each deduplication operation targets
-.IR length
+.IR src_length
bytes in file descriptor
.IR dest_fd
at offset
@@ -108,8 +108,15 @@ During the call,
must be open for reading and
.IR dest_fd
must be open for writing.
-For any call to this ioctl, there may not be more than 65,536
-requests attached; each request may not exceed 16MiB.
+The combined size of the struct
+.IR file_dedupe_range
+and the struct
+.IR file_dedupe_range_info
+array must not exceed the system page size.
+The maximum size of
+.IR src_length
+is filesystem dependent and is typically 16MiB.
+This limit will be enforced silently by the filesystem.
By convention, the storage used by
.IR src_fd
is mapped into
@@ -144,6 +151,13 @@ is set to indicate the error.
.SH ERRORS
Error codes can be one of, but are not limited to, the following:
.TP
+.B ENOMEM
+The kernel was unable to allocate sufficient memory to perform the
+operation or
+.IR dest_count
+is so large that the input argument description spans more than a single
+page of memory.
+.TP
.B EBADF
.IR src_fd
is not open for reading;
--
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