Currently FIEMAP_EXTENT_LAST is not working consistently across different filesystem's fiemap implementations and thus this feature may be broken. So fix the documentation about this flag to meet the right expectations. Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> --- Documentation/filesystems/fiemap.txt | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/fiemap.txt b/Documentation/filesystems/fiemap.txt index f6d9c99103a4..7c5d22511df7 100644 --- a/Documentation/filesystems/fiemap.txt +++ b/Documentation/filesystems/fiemap.txt @@ -71,8 +71,7 @@ allocated is less than would be required to map the requested range, the maximum number of extents that can be mapped in the fm_extent[] array will be returned and fm_mapped_extents will be equal to fm_extent_count. In that case, the last extent in the array will not -complete the requested range and will not have the FIEMAP_EXTENT_LAST -flag set (see the next section on extent flags). +complete the requested range. Each extent is described by a single fiemap_extent structure as returned in fm_extents. @@ -96,7 +95,7 @@ block size of the file system. With the exception of extents flagged as FIEMAP_EXTENT_MERGED, adjacent extents will not be merged. The fe_flags field contains flags which describe the extent returned. -A special flag, FIEMAP_EXTENT_LAST is always set on the last extent in +A special flag, FIEMAP_EXTENT_LAST *may be* set on the last extent in the file so that the process making fiemap calls can determine when no more extents are available, without having to call the ioctl again. @@ -115,8 +114,9 @@ data. Note that the opposite is not true - it would be valid for FIEMAP_EXTENT_NOT_ALIGNED to appear alone. * FIEMAP_EXTENT_LAST -This is the last extent in the file. A mapping attempt past this -extent will return nothing. +This is generally the last extent in the file. A mapping attempt past this +extent may return nothing. But the user must still confirm by trying to map +past this extent, since different filesystems implement this differently. * FIEMAP_EXTENT_UNKNOWN The location of this extent is currently unknown. This may indicate -- 2.21.0
