linux/fs/fat/nfs.c

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fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
/* fs/fat/nfs.c
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/exportfs.h>
#include "fat.h"
/**
* Look up a directory inode given its starting cluster.
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
*/
static struct inode *fat_dget(struct super_block *sb, int i_logstart)
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct hlist_head *head;
struct hlist_node *_p;
struct msdos_inode_info *i;
struct inode *inode = NULL;
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
spin_lock(&sbi->dir_hash_lock);
hlist_for_each_entry(i, _p, head, i_dir_hash) {
BUG_ON(i->vfs_inode.i_sb != sb);
if (i->i_logstart != i_logstart)
continue;
inode = igrab(&i->vfs_inode);
if (inode)
break;
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
}
spin_unlock(&sbi->dir_hash_lock);
return inode;
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
}
static struct inode *fat_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation)
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
{
struct inode *inode;
if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
return NULL;
inode = ilookup(sb, ino);
if (inode && generation && (inode->i_generation != generation)) {
iput(inode);
inode = NULL;
}
return inode;
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
}
/**
* Map a NFS file handle to a corresponding dentry.
* The dentry may or may not be connected to the filesystem root.
*/
struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
fat_nfs_get_inode);
}
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
/*
* Find the parent for a file specified by NFS handle.
* This requires that the handle contain the i_ino of the parent.
*/
struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
return generic_fh_to_parent(sb, fid, fh_len, fh_type,
fat_nfs_get_inode);
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
}
/*
* Find the parent for a directory that is not currently connected to
* the filesystem root.
*
* On entry, the caller holds child_dir->d_inode->i_mutex.
*/
struct dentry *fat_get_parent(struct dentry *child_dir)
{
struct super_block *sb = child_dir->d_sb;
struct buffer_head *bh = NULL;
struct msdos_dir_entry *de;
struct inode *parent_inode = NULL;
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) {
int parent_logstart = fat_get_start(MSDOS_SB(sb), de);
parent_inode = fat_dget(sb, parent_logstart);
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
}
brelse(bh);
return d_obtain_alias(parent_inode);
fat (exportfs): move NFS support code Under memory pressure, the system may evict dentries from cache. When the FAT driver receives a NFS request involving an evicted dentry, it is unable to reconnect it to the filesystem root. This causes the request to fail, often with ENOENT. This is partially due to ineffectiveness of the current FAT NFS implementation, and partially due to an unimplemented fh_to_parent method. The latter can cause file accesses to fail on shares exported with subtree_check. This patch set provides the FAT driver with the ability to reconnect dentries. NFS file handle generation and lookups are simplified and made congruent with ext2. Testing has involved a memory-starved virtual machine running 3.5-rc5 that exports a ~2 GB vfat filesystem containing a kernel tree (~770 MB, ~40000 files, 9 levels). Both 'cp -r' and 'ls -lR' operations were performed from a client, some overlapping, some consecutive. Exports with 'subtree_check' and 'no_subtree_check' have been tested. Note that while this patch set improves FAT's NFS support, it does not eliminate ESTALE errors completely. The following should be considered for NFS clients who are sensitive to ESTALE: * Mounting with lookupcache=none Unfortunately this can degrade performance severely, particularly for deep filesystems. * Incorporating VFS patches to retry ESTALE failures on the client-side, such as https://lkml.org/lkml/2012/6/29/381 * Handling ESTALE errors in client application code This patch: Move NFS-related code into its own C file. No functional changes. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-05 00:14:44 +00:00
}