From 990a64f7e30225a74522a0a9e171666325536cca Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Wed, 8 Jun 2016 12:24:06 +0200 Subject: [PATCH] ioctl_fideduperange.2: srcfix Signed-off-by: Michael Kerrisk --- man2/ioctl_fideduperange.2 | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/man2/ioctl_fideduperange.2 b/man2/ioctl_fideduperange.2 index 0fbc38808..fe9c5f10a 100644 --- a/man2/ioctl_fideduperange.2 +++ b/man2/ioctl_fideduperange.2 @@ -33,10 +33,13 @@ system call can be used to make some of the data in the file appear in the .B dest_fd file by sharing the underlying storage if the file data is identical -("deduplication"). This reduces storage consumption by allowing the filesystem -to store one shared copy of the data. If a file write should occur to a shared +("deduplication"). +This reduces storage consumption by allowing the filesystem +to store one shared copy of the data. +If a file write should occur to a shared region, the filesystem must ensure that the changes remain private to the file -being written. This behavior is commonly referred to as "copy on write". +being written. +This behavior is commonly referred to as "copy on write". This ioctl performs the "compare and share if identical" operation on up to .IR src_length @@ -66,7 +69,8 @@ The fields must be zero. Destinations for the deduplication operation are conveyed in the array at the -end of the structure. The number of destinations is given in +end of the structure. +The number of destinations is given in .IR dest_count ", and the destination information is conveyed in the following form: @@ -126,8 +130,10 @@ regions in directories. .B EINVAL The filesystem does not support deduplicating the ranges of the given files. This error can also appear if either file descriptor represents a device, fifo, -or socket. Disk filesystems generally require the offset and length arguments -to be aligned to the fundamental block size. Neither btrfs nor XFS support +or socket. +Disk filesystems generally require the offset and length arguments +to be aligned to the fundamental block size. +Neither btrfs nor XFS support overlapping deduplication ranges in the same file. .TP .B EBADF @@ -144,7 +150,8 @@ resides on does not support deduplication. is immutable. .TP .B ETXTBSY -One of the files is a swap file. Swap files cannot share storage. +One of the files is a swap file. +Swap files cannot share storage. .TP .B EOPNOTSUPP This can appear if the filesystem does not support deduplicating either file @@ -159,7 +166,8 @@ Some filesystems may limit the amount of data that can be deduplicated in a single call. .SH CONFORMING TO -This API is Linux-specific. This ioctl was previously known as +This API is Linux-specific. +This ioctl was previously known as .B BTRFS_IOC_FILE_EXTENT_SAME and was private to btrfs. .fi