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2022-07-23SUNRPC: Remove xdr_align_data() and xdr_expand_hole()Anna Schumaker
These functions are no longer needed now that the NFS client places data and hole segments directly. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-07-23SUNRPC: Add a function for zeroing out a portion of an xdr_streamAnna Schumaker
This will be used during READ_PLUS decoding for handling HOLE segments. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-07-23SUNRPC: Add a function for directly setting the xdr page lenAnna Schumaker
We need to do this step during READ_PLUS decoding so that we know pages are the right length and any extra data has been preserved in the tail. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-07-23SUNRPC: Introduce xdr_stream_move_subsegment()Anna Schumaker
I do this by creating an xdr subsegment for the range we will be operating over. This lets me shift data to the correct place without potentially overwriting anything already there. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-06-30SUNRPC: Fix READ_PLUS crasherChuck Lever
Looks like there are still cases when "space_left - frag1bytes" can legitimately exceed PAGE_SIZE. Ensure that xdr->end always remains within the current encode buffer. Reported-by: Bruce Fields <bfields@fieldses.org> Reported-by: Zorro Lang <zlang@redhat.com> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216151 Fixes: 6c254bf3b637 ("SUNRPC: Fix the calculation of xdr->end in xdr_get_next_encode_buffer()") Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2022-06-08SUNRPC: Remove pointer type casts from xdr_get_next_encode_buffer()Chuck Lever
To make the code easier to read, remove visual clutter by changing the declared type of @p. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: NeilBrown <neilb@suse.de> Reviewed-by: J. Bruce Fields <bfields@fieldses.org>
2022-06-08SUNRPC: Clean up xdr_get_next_encode_buffer()Chuck Lever
The value of @p is not used until the "location of the next item" is computed. Help human readers by moving its initial assignment to the paragraph where that value is used and by clarifying the antecedents in the documenting comment. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: NeilBrown <neilb@suse.com> Reviewed-by: J. Bruce Fields <bfields@fieldses.org>
2022-06-08SUNRPC: Clean up xdr_commit_encode()Chuck Lever
Both the kvec::iov_len field and the third parameter of memcpy() and memmove() are size_t. There's no reason for the implicit conversion from size_t to int and back. Change the type of @shift to make the code easier to read and understand. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: NeilBrown <neilb@suse.de> Reviewed-by: J. Bruce Fields <bfields@fieldses.org>
2022-06-08SUNRPC: Optimize xdr_reserve_space()Chuck Lever
Transitioning between encode buffers is quite infrequent. It happens about 1 time in 400 calls to xdr_reserve_space(), measured on NFSD with a typical build/test workload. Force the compiler to remove that code from xdr_reserve_space(), which is a hot path on both the server and the client. This change reduces the size of xdr_reserve_space() from 10 cache lines to 2 when compiled with -Os. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: J. Bruce Fields <bfields@fieldses.org>
2022-06-08SUNRPC: Fix the calculation of xdr->end in xdr_get_next_encode_buffer()Chuck Lever
I found that NFSD's new NFSv3 READDIRPLUS XDR encoder was screwing up right at the end of the page array. xdr_get_next_encode_buffer() does not compute the value of xdr->end correctly: * The check to see if we're on the final available page in xdr->buf needs to account for the space consumed by @nbytes. * The new xdr->end value needs to account for the portion of @nbytes that is to be encoded into the previous buffer. Fixes: 2825a7f90753 ("nfsd4: allow encoding across page boundaries") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: NeilBrown <neilb@suse.de> Reviewed-by: J. Bruce Fields <bfields@fieldses.org>
2021-10-02SUNRPC: xdr_stream_subsegment() must handle non-zero page_basesChuck Lever
xdr_stream_subsegment() was introduced in commit c1346a1216ab ("NFSD: Replace the internals of the READ_BUF() macro"). There are two call sites for xdr_stream_subsegment(). One is nfsd4_decode_write(), and the other is nfsd4_decode_setxattr(). Currently neither of these call sites calls this API when xdr_buf::page_base is a non-zero value. However, I'm about to add a case where page_base will sometimes not be zero when nfsd4_decode_write() invokes this API. Replace the logic in xdr_stream_subsegment() that advances to the next data item in the xdr_stream with something more generic in order to handle this new use case. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2021-06-13sunrpc: Avoid a KASAN slab-out-of-bounds bug in xdr_set_page_base()Anna Schumaker
This seems to happen fairly easily during READ_PLUS testing on NFS v4.2. I found that we could end up accessing xdr->buf->pages[pgnr] with a pgnr greater than the number of pages in the array. So let's just return early if we're setting base to a point at the end of the page data and let xdr_set_tail_base() handle setting up the buffer pointers instead. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Fixes: 8d86e373b0ef ("SUNRPC: Clean up helpers xdr_set_iov() and xdr_set_page_base()") Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-17Merge tag 'nfs-for-5.11-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfsLinus Torvalds
Pull NFS client updates from Trond Myklebust: "Highlights include: Features: - NFSv3: Add emulation of lookupp() to improve open_by_filehandle() support - A series of patches to improve readdir performance, particularly with large directories - Basic support for using NFS/RDMA with the pNFS files and flexfiles drivers - Micro-optimisations for RDMA - RDMA tracing improvements Bugfixes: - Fix a long standing bug with xs_read_xdr_buf() when receiving partial pages (Dan Aloni) - Various fixes for getxattr and listxattr, when used over non-TCP transports - Fixes for containerised NFS from Sargun Dhillon - switch nfsiod to be an UNBOUND workqueue (Neil Brown) - READDIR should not ask for security label information if there is no LSM policy (Olga Kornievskaia) - Avoid using interval-based rebinding with TCP in lockd (Calum Mackay) - A series of RPC and NFS layer fixes to support the NFSv4.2 READ_PLUS code - A couple of fixes for pnfs/flexfiles read failover Cleanups: - Various cleanups for the SUNRPC xdr code in conjunction with the READ_PLUS fixes" * tag 'nfs-for-5.11-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (90 commits) NFS/pNFS: Fix a typo in ff_layout_resend_pnfs_read() pNFS/flexfiles: Avoid spurious layout returns in ff_layout_choose_ds_for_read NFSv4/pnfs: Add tracing for the deviceid cache fs/lockd: convert comma to semicolon NFSv4.2: fix error return on memory allocation failure NFSv4.2/pnfs: Don't use READ_PLUS with pNFS yet NFSv4.2: Deal with potential READ_PLUS data extent buffer overflow NFSv4.2: Don't error when exiting early on a READ_PLUS buffer overflow NFSv4.2: Handle hole lengths that exceed the READ_PLUS read buffer NFSv4.2: decode_read_plus_hole() needs to check the extent offset NFSv4.2: decode_read_plus_data() must skip padding after data segment NFSv4.2: Ensure we always reset the result->count in decode_read_plus() SUNRPC: When expanding the buffer, we may need grow the sparse pages SUNRPC: Cleanup - constify a number of xdr_buf helpers SUNRPC: Clean up open coded setting of the xdr_stream 'nwords' field SUNRPC: _copy_to/from_pages() now check for zero length SUNRPC: Cleanup xdr_shrink_bufhead() SUNRPC: Fix xdr_expand_hole() SUNRPC: Fixes for xdr_align_data() SUNRPC: _shift_data_left/right_pages should check the shift length ...
2020-12-14SUNRPC: When expanding the buffer, we may need grow the sparse pagesTrond Myklebust
If we're shifting the page data to the right, and this happens to be a sparse page array, then we may need to allocate new pages in order to receive the data. Reported-by: "Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: Cleanup - constify a number of xdr_buf helpersTrond Myklebust
There are a number of xdr helpers for struct xdr_buf that do not change the structure itself. Mark those as taking const pointers for documentation purposes. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: Clean up open coded setting of the xdr_stream 'nwords' fieldTrond Myklebust
Move the setting of the xdr_stream 'nwords' field into the helpers that reset the xdr_stream cursor. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: _copy_to/from_pages() now check for zero lengthTrond Myklebust
Clean up callers of _copy_to/from_pages() that still check for a zero length. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: Cleanup xdr_shrink_bufhead()Trond Myklebust
Clean up xdr_shrink_bufhead() to use the new helpers instead of doing its own thing. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: Fix xdr_expand_hole()Trond Myklebust
We do want to try to grow the buffer if possible, but if that attempt fails, we still want to move the data and truncate the XDR message. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: Fixes for xdr_align_data()Trond Myklebust
The main use case right now for xdr_align_data() is to shift the page data to the left, and in practice shrink the total XDR data buffer. This patch ensures that we fix up the accounting for the buffer length as we shift that data around. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-14SUNRPC: _shift_data_left/right_pages should check the shift lengthTrond Myklebust
Exit early if the shift is zero. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Fix open coded xdr_stream_remaining()Trond Myklebust
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Fix up xdr_set_page()Trond Myklebust
While we always want to align to the next page and/or the beginning of the tail buffer when we call xdr_set_next_page(), the functions xdr_align_data() and xdr_expand_hole() really want to align to the next object in that next page or tail. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Clean up the handling of page padding in rpc_prepare_reply_pages()Trond Myklebust
rpc_prepare_reply_pages() currently expects the 'hdrsize' argument to contain the length of the data that we expect to want placed in the head kvec plus a count of 1 word of padding that is placed after the page data. This is very confusing when trying to read the code, and sometimes leads to callers adding an arbitrary value of '1' just in order to satisfy the requirement (whether or not the page data actually needs such padding). This patch aims to clarify the code by changing the 'hdrsize' argument to remove that 1 word of padding. This means we need to subtract the padding from all the existing callers. Fixes: 02ef04e432ba ("NFS: Account for XDR pad of buf->pages") Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Fix up xdr_read_pages() to take arbitrary object lengthsTrond Myklebust
Fix up xdr_read_pages() so that it can handle object lengths that are larger than the page length, by simply aligning to the next object in the buffer tail. The function will continue to return the length of the truncate object data that actually fit into the pages. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Clean up helpers xdr_set_iov() and xdr_set_page_base()Trond Myklebust
Allow xdr_set_iov() to set a base so that we can use it to set the cursor to a specific position in the kvec buffer. If the new base overflows the kvec/pages buffer in either xdr_set_iov() or xdr_set_page_base(), then truncate it so that we point to the end of the buffer. Finally, change both function to return the number of bytes remaining to read in their buffers. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Fix up typo in xdr_init_decode()Trond Myklebust
We already know that the head buffer and page are empty, so if there is any data, it is in the tail. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02SUNRPC: Fix up open coded kmemdup_nul()Trond Myklebust
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-11-30NFSD: Replace the internals of the READ_BUF() macroChuck Lever
Convert the READ_BUF macro in nfs4xdr.c from open code to instead use the new xdr_stream-style decoders already in use by the encode side (and by the in-kernel NFS client implementation). Once this conversion is done, each individual NFSv4 argument decoder can be independently cleaned up to replace these macros with C code. Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30SUNRPC: Add xdr_set_scratch_page() and xdr_reset_scratch_buffer()Chuck Lever
Clean up: De-duplicate some frequently-used code. Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30SUNRPC: Adjust synopsis of xdr_buf_subsegment()Chuck Lever
Clean up: This enables xdr_buf_subsegment()'s callers to pass in a const pointer to that buffer. Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-10-22Merge tag 'nfsd-5.10' of git://linux-nfs.org/~bfields/linuxLinus Torvalds
Pull nfsd updates from Bruce Fields: "The one new feature this time, from Anna Schumaker, is READ_PLUS, which has the same arguments as READ but allows the server to return an array of data and hole extents. Otherwise it's a lot of cleanup and bugfixes" * tag 'nfsd-5.10' of git://linux-nfs.org/~bfields/linux: (43 commits) NFSv4.2: Fix NFS4ERR_STALE error when doing inter server copy SUNRPC: fix copying of multiple pages in gss_read_proxy_verf() sunrpc: raise kernel RPC channel buffer size svcrdma: fix bounce buffers for unaligned offsets and multiple pages nfsd: remove unneeded break net/sunrpc: Fix return value for sysctl sunrpc.transports NFSD: Encode a full READ_PLUS reply NFSD: Return both a hole and a data segment NFSD: Add READ_PLUS hole segment encoding NFSD: Add READ_PLUS data support NFSD: Hoist status code encoding into XDR encoder functions NFSD: Map nfserr_wrongsec outside of nfsd_dispatch NFSD: Remove the RETURN_STATUS() macro NFSD: Call NFSv2 encoders on error returns NFSD: Fix .pc_release method for NFSv2 NFSD: Remove vestigial typedefs NFSD: Refactor nfsd_dispatch() error paths NFSD: Clean up nfsd_dispatch() variables NFSD: Clean up stale comments in nfsd_dispatch() NFSD: Clean up switch statement in nfsd_dispatch() ...
2020-10-07SUNRPC: Add an xdr_align_data() functionAnna Schumaker
For now, this function simply aligns the data at the beginning of the pages. This can eventually be expanded to shift data to the correct offsets when we're ready. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-10-07SUNRPC: Add the ability to expand holes in data pagesAnna Schumaker
This patch adds the ability to "read a hole" into a set of XDR data pages by taking the following steps: 1) Shift all data after the current xdr->p to the right, possibly into the tail, 2) Zero the specified range, and 3) Update xdr->p to point beyond the hole. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-10-07SUNRPC: Split out _shift_data_right_tail()Anna Schumaker
xdr_shrink_pagelen() is very similar to what we need for hole expansion, so split out the common code into its own function that can be used by both functions. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-10-07SUNRPC: Split out xdr_realign_pages() from xdr_align_pages()Anna Schumaker
I don't need the entire align pages code for READ_PLUS, so split out the part I do need so I don't need to reimplement anything. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-10-07SUNRPC: Implement a xdr_page_pos() functionAnna Schumaker
I'll need this for READ_PLUS to help figure out the offset where page data is stored at, but it might also be useful for other things. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-10-07SUNRPC: Split out a function for setting current pageAnna Schumaker
I'm going to need this bit of code in a few places for READ_PLUS decoding, so let's make it a helper function. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-25SUNRPC/NFSD: Implement xdr_reserve_space_vec()Anna Schumaker
Reserving space for a large READ payload requires special handling when reserving space in the xdr buffer pages. One problem we can have is use of the scratch buffer, which is used to get a pointer to a contiguous region of data up to PAGE_SIZE. When using the scratch buffer, calls to xdr_commit_encode() shift the data to it's proper alignment in the xdr buffer. If we've reserved several pages in a vector, then this could potentially invalidate earlier pointers and result in incorrect READ data being sent to the client. I get around this by looking at the amount of space left in the current page, and never reserve more than that for each entry in the read vector. This lets us place data directly where it needs to go in the buffer pages. Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-09-25net: sunrpc: delete repeated wordsRandy Dunlap
Drop duplicate words in net/sunrpc/. Also fix "Anyone" to be "Any one". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: linux-nfs@vger.kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-06-26SUNRPC: Properly set the @subbuf parameter of xdr_buf_subsegment()Chuck Lever
@subbuf is an output parameter of xdr_buf_subsegment(). A survey of call sites shows that @subbuf is always uninitialized before xdr_buf_segment() is invoked by callers. There are some execution paths through xdr_buf_subsegment() that do not set all of the fields in @subbuf, leaving some pointer fields containing garbage addresses. Subsequent processing of that buffer then results in a page fault. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-04-27SUNRPC: Revert 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()")Chuck Lever
I've noticed that when krb5i or krb5p security is in use, retransmitted requests are missing the server's duplicate reply cache. The computed checksum on the retransmitted request does not match the cached checksum, resulting in the server performing the retransmitted request again instead of returning the cached reply. The assumptions made when removing xdr_buf_trim() were not correct. In the send paths, the upper layer has already set the segment lengths correctly, and shorting the buffer's content is simply a matter of reducing buf->len. xdr_buf_trim() is the right answer in the receive/unwrap path on both the client and the server. The buffer segment lengths have to be shortened one-by-one. On the server side in particular, head.iov_len needs to be updated correctly to enable nfsd_cache_csum() to work correctly. The simple buf->len computation doesn't do that, and that results in checksumming stale data in the buffer. The problem isn't noticed until there's significant instability of the RPC transport. At that point, the reliability of retransmit detection on the server becomes crucial. Fixes: 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()") Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-03-16SUNRPC: Remove xdr_buf_read_mic()Chuck Lever
Clean up: this function is no longer used. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Benjamin Coddington <bcodding@redhat.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-01-15SUNRPC: constify copied structureJulia Lawall
The empty_iov structure is only copied into another structure, so make it const. The opportunity for this change was found using Coccinelle. Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-11-18SUNRPC: Fix another issue with MIC buffer spaceChuck Lever
xdr_shrink_pagelen() BUG's when @len is larger than buf->page_len. This can happen when xdr_buf_read_mic() is given an xdr_buf with a small page array (like, only a few bytes). Instead, just cap the number of bytes that xdr_shrink_pagelen() will move. Fixes: 5f1bc39979d ("SUNRPC: Fix buffer handling of GSS MIC ... ") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Benjamin Coddington <bcodding@redhat.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2019-09-20SUNRPC: Rename xdr_buf_read_netobj to xdr_buf_read_micBenjamin Coddington
Let the name reflect the single use. The function now assumes the GSS MIC is the last object in the buffer. Signed-off-by: Benjamin Coddington <bcodding@redhat.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-09-20SUNRPC: Fix buffer handling of GSS MIC without slackBenjamin Coddington
The GSS Message Integrity Check data for krb5i may lie partially in the XDR reply buffer's pages and tail. If so, we try to copy the entire MIC into free space in the tail. But as the estimations of the slack space required for authentication and verification have improved there may be less free space in the tail to complete this copy -- see commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply buffer size"). In fact, there may only be room in the tail for a single copy of the MIC, and not part of the MIC and then another complete copy. The real world failure reported is that `ls` of a directory on NFS may sometimes return -EIO, which can be traced back to xdr_buf_read_netobj() failing to find available free space in the tail to copy the MIC. Fix this by checking for the case of the MIC crossing the boundaries of head, pages, and tail. If so, shift the buffer until the MIC is contained completely within the pages or tail. This allows the remainder of the function to create a sub buffer that directly address the complete MIC. Signed-off-by: Benjamin Coddington <bcodding@redhat.com> Cc: stable@vger.kernel.org # v5.1 Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-08-20SUNRPC: Inline xdr_commit_encodeChuck Lever
Micro-optimization: For xdr_commit_encode call sites in net/sunrpc/xdr.c, eliminate the extra calling sequence. On my client, this change saves about a microsecond for every 30 calls to xdr_reserve_space(). Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-05-21treewide: Add SPDX license identifier for missed filesThomas Gleixner
Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-14NFS: Account for XDR pad of buf->pagesChuck Lever
Certain NFS results (eg. READLINK) might expect a data payload that is not an exact multiple of 4 bytes. In this case, XDR encoding is required to pad that payload so its length on the wire is a multiple of 4 bytes. The constants that define the maximum size of each NFS result do not appear to account for this extra word. In each case where the data payload is to be received into pages: - 1 word is added to the size of the receive buffer allocated by call_allocate - rpc_inline_rcv_pages subtracts 1 word from @hdrsize so that the extra buffer space falls into the rcv_buf's tail iovec - If buf->pagelen is word-aligned, an XDR pad is not needed and is thus removed from the tail Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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