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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/filesystems/ext4/ifork.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
Diffstat (limited to 'Documentation/filesystems/ext4/ifork.rst')
-rw-r--r-- | Documentation/filesystems/ext4/ifork.rst | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/Documentation/filesystems/ext4/ifork.rst b/Documentation/filesystems/ext4/ifork.rst new file mode 100644 index 000000000..dc31f505e --- /dev/null +++ b/Documentation/filesystems/ext4/ifork.rst @@ -0,0 +1,194 @@ +.. SPDX-License-Identifier: GPL-2.0 + +The Contents of inode.i_block +------------------------------ + +Depending on the type of file an inode describes, the 60 bytes of +storage in ``inode.i_block`` can be used in different ways. In general, +regular files and directories will use it for file block indexing +information, and special files will use it for special purposes. + +Symbolic Links +~~~~~~~~~~~~~~ + +The target of a symbolic link will be stored in this field if the target +string is less than 60 bytes long. Otherwise, either extents or block +maps will be used to allocate data blocks to store the link target. + +Direct/Indirect Block Addressing +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In ext2/3, file block numbers were mapped to logical block numbers by +means of an (up to) three level 1-1 block map. To find the logical block +that stores a particular file block, the code would navigate through +this increasingly complicated structure. Notice that there is neither a +magic number nor a checksum to provide any level of confidence that the +block isn't full of garbage. + +.. ifconfig:: builder != 'latex' + + .. include:: blockmap.rst + +.. ifconfig:: builder == 'latex' + + [Table omitted because LaTeX doesn't support nested tables.] + +Note that with this block mapping scheme, it is necessary to fill out a +lot of mapping data even for a large contiguous file! This inefficiency +led to the creation of the extent mapping scheme, discussed below. + +Notice also that a file using this mapping scheme cannot be placed +higher than 2^32 blocks. + +Extent Tree +~~~~~~~~~~~ + +In ext4, the file to logical block map has been replaced with an extent +tree. Under the old scheme, allocating a contiguous run of 1,000 blocks +requires an indirect block to map all 1,000 entries; with extents, the +mapping is reduced to a single ``struct ext4_extent`` with +``ee_len = 1000``. If flex_bg is enabled, it is possible to allocate +very large files with a single extent, at a considerable reduction in +metadata block use, and some improvement in disk efficiency. The inode +must have the extents flag (0x80000) flag set for this feature to be in +use. + +Extents are arranged as a tree. Each node of the tree begins with a +``struct ext4_extent_header``. If the node is an interior node +(``eh.eh_depth`` > 0), the header is followed by ``eh.eh_entries`` +instances of ``struct ext4_extent_idx``; each of these index entries +points to a block containing more nodes in the extent tree. If the node +is a leaf node (``eh.eh_depth == 0``), then the header is followed by +``eh.eh_entries`` instances of ``struct ext4_extent``; these instances +point to the file's data blocks. The root node of the extent tree is +stored in ``inode.i_block``, which allows for the first four extents to +be recorded without the use of extra metadata blocks. + +The extent tree header is recorded in ``struct ext4_extent_header``, +which is 12 bytes long: + +.. list-table:: + :widths: 8 8 24 40 + :header-rows: 1 + + * - Offset + - Size + - Name + - Description + * - 0x0 + - __le16 + - eh_magic + - Magic number, 0xF30A. + * - 0x2 + - __le16 + - eh_entries + - Number of valid entries following the header. + * - 0x4 + - __le16 + - eh_max + - Maximum number of entries that could follow the header. + * - 0x6 + - __le16 + - eh_depth + - Depth of this extent node in the extent tree. 0 = this extent node + points to data blocks; otherwise, this extent node points to other + extent nodes. The extent tree can be at most 5 levels deep: a logical + block number can be at most ``2^32``, and the smallest ``n`` that + satisfies ``4*(((blocksize - 12)/12)^n) >= 2^32`` is 5. + * - 0x8 + - __le32 + - eh_generation + - Generation of the tree. (Used by Lustre, but not standard ext4). + +Internal nodes of the extent tree, also known as index nodes, are +recorded as ``struct ext4_extent_idx``, and are 12 bytes long: + +.. list-table:: + :widths: 8 8 24 40 + :header-rows: 1 + + * - Offset + - Size + - Name + - Description + * - 0x0 + - __le32 + - ei_block + - This index node covers file blocks from 'block' onward. + * - 0x4 + - __le32 + - ei_leaf_lo + - Lower 32-bits of the block number of the extent node that is the next + level lower in the tree. The tree node pointed to can be either another + internal node or a leaf node, described below. + * - 0x8 + - __le16 + - ei_leaf_hi + - Upper 16-bits of the previous field. + * - 0xA + - __u16 + - ei_unused + - + +Leaf nodes of the extent tree are recorded as ``struct ext4_extent``, +and are also 12 bytes long: + +.. list-table:: + :widths: 8 8 24 40 + :header-rows: 1 + + * - Offset + - Size + - Name + - Description + * - 0x0 + - __le32 + - ee_block + - First file block number that this extent covers. + * - 0x4 + - __le16 + - ee_len + - Number of blocks covered by extent. If the value of this field is <= + 32768, the extent is initialized. If the value of the field is > 32768, + the extent is uninitialized and the actual extent length is ``ee_len`` - + 32768. Therefore, the maximum length of a initialized extent is 32768 + blocks, and the maximum length of an uninitialized extent is 32767. + * - 0x6 + - __le16 + - ee_start_hi + - Upper 16-bits of the block number to which this extent points. + * - 0x8 + - __le32 + - ee_start_lo + - Lower 32-bits of the block number to which this extent points. + +Prior to the introduction of metadata checksums, the extent header + +extent entries always left at least 4 bytes of unallocated space at the +end of each extent tree data block (because (2^x % 12) >= 4). Therefore, +the 32-bit checksum is inserted into this space. The 4 extents in the +inode do not need checksumming, since the inode is already checksummed. +The checksum is calculated against the FS UUID, the inode number, the +inode generation, and the entire extent block leading up to (but not +including) the checksum itself. + +``struct ext4_extent_tail`` is 4 bytes long: + +.. list-table:: + :widths: 8 8 24 40 + :header-rows: 1 + + * - Offset + - Size + - Name + - Description + * - 0x0 + - __le32 + - eb_checksum + - Checksum of the extent block, crc32c(uuid+inum+igeneration+extentblock) + +Inline Data +~~~~~~~~~~~ + +If the inline data feature is enabled for the filesystem and the flag is +set for the inode, it is possible that the first 60 bytes of the file +data are stored here. |