User`s guide

File Systems

• Add backup mount option. (3.2)

• Allow larger rsize (up to 16 MB) and change the default to 1 MB. (3.2)

• Introduce credit-based flow control. (3.4)

• Add the cache=strict|none mount option to specify the cache type instead of the strictcache and

forcedirectio options. The legacy options are now mutually exclusive. (3.5)

• The vers=2.1 mount option forces an SMB2 mount. By default, vers=1 (CIFS) is used. (3.5)

• The vers=2.0 mount option forces an SMB2.02 mount. (3.8)

ext4

• Reduce CPU overhead when appending files preallocated using fallocate() with mode

FALLOC_FL_KEEP_SIZE via direct I/O. (3.2)

• Reduce CPU overhead by optimizing memmove() lengths in extent and index insertions. (3.2)

• Support block sizes of up to 1 MB using the -C option to mkfs.ext4. This change is not backwards

compatible with older kernels. (3.2)

• Remove the resize and journal=update mount option. (3.4)

• Improve performance of truncate and unlink. (3.7)

• Support online resizing of metablock group (META_BG) and 64-bit file systems. (3.7)

• Add max_dir_size_kb mount option to specify a maximum directory size. (3.7)

• Re-enable -o discard functionality in no-journal mode. (3.7)

• Remove support for disabling extended attributes. (3.8)

• Implement support for SEEK_DATA and SEEK_HOLE. (3.8)

NFS

• Add support for the RAID-5 read-4-write interface. (3.2)

• Add v4.0 and v4.1 mount options. (3.4)

• The kernel can deduce the value of clientaddr if this mount option is not specified for NFS v4. (3.4)

• Add the migration mount option that specifies whether a server supports Transparent State Migration

(TSM). (3.7)

• Handle IPv6 remote addresses from GETDEVICEINFO (required for pNFS). (3.8)

• Remove the deprecated nfsctl() system call and all related code. (3.8)

pstore

• Add runtime logging support for kernel messages to allow debugging of hangs caused by hardware

issues. (3.6)

• Add console message handling. The log size is configurable by using the ramoops.console_size

module option, and the log is accessible at pstore-mountpoint/console-ramoops. (3.6)