21b6633d51
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>
11 lines
259 B
Makefile
11 lines
259 B
Makefile
#
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# Makefile for the Linux fat filesystem support.
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#
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obj-$(CONFIG_FAT_FS) += fat.o
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obj-$(CONFIG_VFAT_FS) += vfat.o
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obj-$(CONFIG_MSDOS_FS) += msdos.o
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fat-y := cache.o dir.o fatent.o file.o inode.o misc.o nfs.o
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vfat-y := namei_vfat.o
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msdos-y := namei_msdos.o
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