NFS: don't unhash dentry during unlink/rename

NFS unlink() (and rename over existing target) must determine if the
file is open, and must perform a "silly rename" instead of an unlink (or
before ren

NFS: don't unhash dentry during unlink/rename

NFS unlink() (and rename over existing target) must determine if the
file is open, and must perform a "silly rename" instead of an unlink (or
before rename) if it is. Otherwise the client might hold a file open
which has been removed on the server.

Consequently if it determines that the file isn't open, it must block
any subsequent opens until the unlink/rename has been completed on the
server.

This is currently achieved by unhashing the dentry. This forces any
open attempt to the slow-path for lookup which will block on i_rwsem on
the directory until the unlink/rename completes. A future patch will
change the VFS to only get a shared lock on i_rwsem for unlink, so this
will no longer work.

Instead we introduce an explicit interlock. A special value is stored
in dentry->d_fsdata while the unlink/rename is running and
->d_revalidate blocks while that value is present. When ->d_revalidate
unblocks, the dentry will be invalid. This closes the race
without requiring exclusion on i_rwsem.

d_fsdata is already used in two different ways.
1/ an IS_ROOT directory dentry might have a "devname" stored in
d_fsdata. Such a dentry doesn't have a name and so cannot be the
target of unlink or rename. For safety we check if an old devname
is still stored, and remove it if it is.
2/ a dentry with DCACHE_NFSFS_RENAMED set will have a 'struct
nfs_unlinkdata' stored in d_fsdata. While this is set maydelete()
will fail, so an unlink or rename will never proceed on such
a dentry.

Neither of these can be in effect when a dentry is the target of unlink
or rename. So we can expect d_fsdata to be NULL, and store a special
value ((void*)1) which is given the name NFS_FSDATA_BLOCKED to indicate
that any lookup will be blocked.

The d_count() is incremented under d_lock() when a lookup finds the
dentry, so we check d_count() is low, and set NFS_FSDATA_BLOCKED under
the same lock to avoid any races.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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nfs: Replace kmap() with kmap_local_page()

The use of kmap() is being deprecated in favor of kmap_local_page().

With kmap_local_page(), the mapping is per thread, CPU local and not
globally visible

nfs: Replace kmap() with kmap_local_page()

The use of kmap() is being deprecated in favor of kmap_local_page().

With kmap_local_page(), the mapping is per thread, CPU local and not
globally visible. Furthermore, the mapping can be acquired from any context
(including interrupts).

Therefore, use kmap_local_page() in nfs_do_filldir() because this mapping
is per thread, CPU local, and not globally visible.

Suggested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Fix case insensitive renames

For filesystems that are case insensitive and case preserving, we need
to be able to rename from one case folded variant of the filename to
another.
Currently, if w

NFS: Fix case insensitive renames

For filesystems that are case insensitive and case preserving, we need
to be able to rename from one case folded variant of the filename to
another.
Currently, if we have looked up the target filename before the call to
rename, then we may have a hashed dentry with that target name in the
dcache, causing the vfs to optimise away the rename.
To avoid that, let's drop the target dentry, and leave it to the server
to optimise away the rename if that is the correct thing to do.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFSv4: Add FMODE_CAN_ODIRECT after successful open of a NFS4.x file

Commit a2ad63daa88b ("VFS: add FMODE_CAN_ODIRECT file flag")
added the FMODE_CAN_ODIRECT flag for NFSv3 but neglected to add
it fo

NFSv4: Add FMODE_CAN_ODIRECT after successful open of a NFS4.x file

Commit a2ad63daa88b ("VFS: add FMODE_CAN_ODIRECT file flag")
added the FMODE_CAN_ODIRECT flag for NFSv3 but neglected to add
it for NFSv4.x. This causes direct io on NFSv4.x to fail open
with EINVAL:
mount -o vers=4.2 127.0.0.1:/export /mnt/nfs4
dd if=/dev/zero of=/mnt/nfs4/file.bin bs=128k count=1 oflag=direct
dd: failed to open '/mnt/nfs4/file.bin': Invalid argument
dd of=/dev/null if=/mnt/nfs4/file.bin bs=128k count=1 iflag=direct
dd: failed to open '/mnt/dir1/file1.bin': Invalid argument

Fixes: a2ad63daa88b ("VFS: add FMODE_CAN_ODIRECT file flag")
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

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nfs: Convert to free_folio

Add a wrapper that converts back from the folio to the page. This
entire file needs to be converted to use folios, but that's a
task for a different set of patches.

Sign

nfs: Convert to free_folio

Add a wrapper that converts back from the folio to the page. This
entire file needs to be converted to use folios, but that's a
task for a different set of patches.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

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NFS: Replace readdir's use of xxhash() with hash_64()

Both xxhash() and hash_64() appear to give similarly low collision
rates with a standard linearly increasing readdir offset. They both give
simi

NFS: Replace readdir's use of xxhash() with hash_64()

Both xxhash() and hash_64() appear to give similarly low collision
rates with a standard linearly increasing readdir offset. They both give
similarly higher collision rates when applied to ext4's offsets.

So switch to using the standard hash_64().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFSv4: fix open failure with O_ACCMODE flag

open() with O_ACCMODE|O_DIRECT flags secondly will fail.

Reproducer:
1. mount -t nfs -o vers=4.2 $server_ip:/ /mnt/
2. fd = open("/mnt/file", O_ACCMO

NFSv4: fix open failure with O_ACCMODE flag

open() with O_ACCMODE|O_DIRECT flags secondly will fail.

Reproducer:
1. mount -t nfs -o vers=4.2 $server_ip:/ /mnt/
2. fd = open("/mnt/file", O_ACCMODE|O_DIRECT|O_CREAT)
3. close(fd)
4. fd = open("/mnt/file", O_ACCMODE|O_DIRECT)

Server nfsd4_decode_share_access() will fail with error nfserr_bad_xdr when
client use incorrect share access mode of 0.

Fix this by using NFS4_SHARE_ACCESS_BOTH share access mode in client,
just like firstly opening.

Fixes: ce4ef7c0a8a05 ("NFS: Split out NFS v4 file operations")
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Fix revalidation of empty readdir pages

If the page is empty, we need to check the array->last_cookie instead of
the first entry. Add a helper for the cases where we care.

Signed-off-by: Trond

NFS: Fix revalidation of empty readdir pages

If the page is empty, we need to check the array->last_cookie instead of
the first entry. Add a helper for the cases where we care.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Don't deadlock when cookie hashes collide

In the very rare case where the readdir reply contains multiple cookies
that map to the same hash value, we can end up deadlocking waiting for a
page l

NFS: Don't deadlock when cookie hashes collide

In the very rare case where the readdir reply contains multiple cookies
that map to the same hash value, we can end up deadlocking waiting for a
page lock that we already hold. In this case we should fail the page
lock by using grab_cache_page_nowait().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Cache all entries in the readdirplus reply

Even if we're not able to cache all the entries in the readdir buffer,
let's ensure that we do prime the dcache.

Signed-off-by: Trond Myklebust <tron

NFS: Cache all entries in the readdirplus reply

Even if we're not able to cache all the entries in the readdir buffer,
let's ensure that we do prime the dcache.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Optimise away the previous cookie field

Replace the 'previous cookie' field in struct nfs_entry with the
array->last_cookie.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Fix up forced readdirplus

Avoid clearing the entire readdir page cache if we're just doing forced
readdirplus for the 'ls -l' heuristic.

Signed-off-by: Trond Myklebust <trond.myklebust@hammers

NFS: Fix up forced readdirplus

Avoid clearing the entire readdir page cache if we're just doing forced
readdirplus for the 'ls -l' heuristic.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Convert readdir page cache to use a cookie based index

Instead of using a linear index to address the pages, use the cookie of
the first entry, since that is what we use to match the page anywa

NFS: Convert readdir page cache to use a cookie based index

Instead of using a linear index to address the pages, use the cookie of
the first entry, since that is what we use to match the page anyway.

This allows us to avoid re-reading the entire cache on a seekdir() type
of operation. The latter is very common when re-exporting NFS, and is a
major performance drain.

The change does affect our duplicate cookie detection, since we can no
longer rely on the page index as a linear offset for detecting whether
we looped backwards. However since we no longer do a linear search
through all the pages on each call to nfs_readdir(), this is less of a
concern than it was previously.
The other downside is that invalidate_mapping_pages() no longer can use
the page index to avoid clearing pages that have been read. A subsequent
patch will restore the functionality this provides to the 'ls -l'
heuristic.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Clean up page array initialisation/free

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Trace effects of the readdirplus heuristic

Enable tracking of when the readdirplus heuristic causes a page cache
invalidation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Trace effects of readdirplus on the dcache

Trace the effects of readdirplus on attribute and dentry revalidation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Add basic readdir tracing

Add tracing to track how often the client goes to the server for updated
readdir information.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFS: Don't request readdirplus when revalidation was forced

If the revalidation was forced, due to the presence of a LOOKUP_EXCL or
a LOOKUP_REVAL flag, then readdirplus won't help. It also can't he

NFS: Don't request readdirplus when revalidation was forced

If the revalidation was forced, due to the presence of a LOOKUP_EXCL or
a LOOKUP_REVAL flag, then readdirplus won't help. It also can't help
when we're doing a path component lookup.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Readdirplus can't help lookup for case insensitive filesystems

If the filesystem is case insensitive, then readdirplus can't help with
cache misses, since it won't return case folded variants o

NFS: Readdirplus can't help lookup for case insensitive filesystems

If the filesystem is case insensitive, then readdirplus can't help with
cache misses, since it won't return case folded variants of the filename.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Improve heuristic for readdirplus

The heuristic for readdirplus is designed to try to detect 'ls -l' and
similar patterns. It does so by looking for cache hit/miss patterns in
both the attribut

NFS: Improve heuristic for readdirplus

The heuristic for readdirplus is designed to try to detect 'ls -l' and
similar patterns. It does so by looking for cache hit/miss patterns in
both the attribute cache and in the dcache of the files in a given
directory, and then sets a flag for the readdirplus code to interpret.

The problem with this approach is that a single attribute or dcache miss
can cause the NFS code to force a refresh of the attributes for the
entire set of files contained in the directory.

To be able to make a more nuanced decision, let's sample the number of
hits and misses in the set of open directory descriptors. That allows us
to set thresholds at which we start preferring READDIRPLUS over regular
READDIR, or at which we start to force a re-read of the remaining
readdir cache using READDIRPLUS.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Reduce use of uncached readdir

When reading a very large directory, we want to try to keep the page
cache up to date if doing so is inexpensive. With the change to allow
readdir to continue rea

NFS: Reduce use of uncached readdir

When reading a very large directory, we want to try to keep the page
cache up to date if doing so is inexpensive. With the change to allow
readdir to continue reading even when the cache is incomplete, we no
longer need to fall back to uncached readdir in order to scale to large
directories.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Simplify nfs_readdir_xdr_to_array()

Recent changes to readdir mean that we can cope with partially filled
page cache entries, so we no longer need to rely on looping in
nfs_readdir_xdr_to_array

NFS: Simplify nfs_readdir_xdr_to_array()

Recent changes to readdir mean that we can cope with partially filled
page cache entries, so we no longer need to rely on looping in
nfs_readdir_xdr_to_array().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: If the cookie verifier changes, we must invalidate the page cache

Ensure that if the cookie verifier changes when we use the zero-valued
cookie, then we invalidate any cached pages.

Signed-off

NFS: If the cookie verifier changes, we must invalidate the page cache

Ensure that if the cookie verifier changes when we use the zero-valued
cookie, then we invalidate any cached pages.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Adjust the amount of readahead performed by NFS readdir

The current NFS readdir code will always try to maximise the amount of
readahead it performs on the assumption that we can cache anything

NFS: Adjust the amount of readahead performed by NFS readdir

The current NFS readdir code will always try to maximise the amount of
readahead it performs on the assumption that we can cache anything that
isn't immediately read by the process.
There are several cases where this assumption breaks down, including
when the 'ls -l' heuristic kicks in to try to force use of readdirplus
as a batch replacement for lookup/getattr.

This patch therefore tries to tone down the amount of readahead we
perform, and adjust it to try to match the amount of data being
requested by user space.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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NFS: Don't advance the page pointer unless the page is full

When we hit the end of the data in the readdir page, we don't want to
start filling a new page, unless this one is full.

Signed-off-by: T

NFS: Don't advance the page pointer unless the page is full

When we hit the end of the data in the readdir page, we don't want to
start filling a new page, unless this one is full.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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