- 24 Apr, 2015 2 commits
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Jens Axboe authored
do_blockdev_direct_IO() increments and decrements the inode ->i_dio_count for each IO operation. It does this to protect against truncate of a file. Block devices don't need this sort of protection. For a capable multiqueue setup, this atomic int is the only shared state between applications accessing the device for O_DIRECT, and it presents a scaling wall for that. In my testing, as much as 30% of system time is spent incrementing and decrementing this value. A mixed read/write workload improved from ~2.5M IOPS to ~9.6M IOPS, with better latencies too. Before: clat percentiles (usec): | 1.00th=[ 33], 5.00th=[ 34], 10.00th=[ 34], 20.00th=[ 34], | 30.00th=[ 34], 40.00th=[ 34], 50.00th=[ 35], 60.00th=[ 35], | 70.00th=[ 35], 80.00th=[ 35], 90.00th=[ 37], 95.00th=[ 80], | 99.00th=[ 98], 99.50th=[ 151], 99.90th=[ 155], 99.95th=[ 155], | 99.99th=[ 165] After: clat percentiles (usec): | 1.00th=[ 95], 5.00th=[ 108], 10.00th=[ 129], 20.00th=[ 149], | 30.00th=[ 155], 40.00th=[ 161], 50.00th=[ 167], 60.00th=[ 171], | 70.00th=[ 177], 80.00th=[ 185], 90.00th=[ 201], 95.00th=[ 270], | 99.00th=[ 390], 99.50th=[ 398], 99.90th=[ 418], 99.95th=[ 422], | 99.99th=[ 438] In other setups, Robert Elliott reported seeing good performance improvements: https://lkml.org/lkml/2015/4/3/557 The more applications accessing the device, the worse it gets. Add a new direct-io flags, DIO_SKIP_DIO_COUNT, which tells do_blockdev_direct_IO() that it need not worry about incrementing or decrementing the inode i_dio_count for this caller. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Elliott, Robert (Server Storage) <elliott@hp.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
Jens Axboe <axboe@fb.com> Signed-off-by:
Al Viro <viro@zeniv.linux.org.uk>
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Johannes Berg authored
Al Viro's IOV changes broke 9p readdir() because the new code didn't abort the read when it returned nothing. The original code checked if the combined error/length was <= 0 but in the new code that accidentally got changed to just an error check. Add back the return from the function when nothing is read. Cc: Al Viro <viro@zeniv.linux.org.uk> Fixes: e1200fe6 ("9p: switch p9_client_read() to passing struct iov_iter *") Signed-off-by:
Johannes Berg <johannes.berg@intel.com> Signed-off-by:
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- 15 Apr, 2015 24 commits
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David Howells authored
Signed-off-by:
David Howells <dhowells@redhat.com> Signed-off-by:
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David Howells authored
these should be used on objects already in top layer Signed-off-by:
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David Howells authored
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David Howells authored
library helpers called by filesystem drivers on their own inodes Signed-off-by:
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David Howells authored
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David Howells authored
that's the bulk of filesystem drivers dealing with inodes of their own Signed-off-by:
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David Howells authored
... except where that code acts as a filesystem driver, rather than working with dentries given to it. Signed-off-by:
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David Howells authored
most of the ->d_inode uses there refer to the same inode IO would go to, i.e. d_backing_inode() Signed-off-by:
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David Howells authored
socket inodes and sunrpc filesystems - inodes owned by that code Signed-off-by:
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David Howells authored
places where we are dealing with S_ISSOCK file creation/lookups. Signed-off-by:
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David Howells authored
relayfs and tracefs are dealing with inodes of their own; those two act as filesystem drivers Signed-off-by:
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David Howells authored
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David Howells authored
Fix up some ->d_inode accesses in the chelsio driver. (1) FILE_DATA() should just be replaced with file_inode(). (2) set_debugfs_file_size() should be removed and debugfs_create_file_size() should be used to create the file. Signed-off-by: -
David Howells authored
Cachefiles should perform fs modifications (eg. vfs_unlink()) on the top layer only and should not attempt to alter the lower layer. Signed-off-by:
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David Howells authored
AF_UNIX sockets should call mknod on the top layer only and should not attempt to modify the lower layer in a layered filesystem such as overlayfs. Signed-off-by:
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Christoph Hellwig authored
Signed-off-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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David Howells authored
Fix inconsistent use of file_inode() vs file->f_path.dentry->d_inode. Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:
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David Howells authored
Make pathwalk use d_is_reg() rather than S_ISREG() to determine whether to honour O_TRUNC. Since this occurs after complete_walk(), the dentry type field cannot change and the inode pointer cannot change as we hold a ref on the dentry, so this should be safe. Signed-off-by:
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David Howells authored
Fix up debugfs to use d_is_dir(dentry) in place of S_ISDIR(dentry->d_inode->i_mode). Signed-off-by:
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David Howells authored
Where we have: if (!dentry->d_inode || d_is_negative(dentry)) { type constructions in pathwalk we should be able to eliminate the check of d_inode and rely solely on the result of d_is_negative() or d_is_positive(). What we do have to take care to do is to read d_inode after calling a d_is_xxx() typecheck function to get the barriering right. Signed-off-by: -
David Howells authored
Don't use d_inode as a variable name as it now masks a function name. Signed-off-by:
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David Howells authored
Impose ordering on accesses of d_inode and d_flags to avoid the need to do this: if (!dentry->d_inode || d_is_negative(dentry)) { when this: if (d_is_negative(dentry)) { should suffice. This check is especially problematic if a dentry can have its type field set to something other than DENTRY_MISS_TYPE when d_inode is NULL (as in unionmount). What we really need to do is stick a write barrier between setting d_inode and setting d_flags and a read barrier between reading d_flags and reading d_inode. Signed-off-by: -
David Howells authored
Supply two functions to test whether a filesystem's own dentries are positive or negative (d_really_is_positive() and d_really_is_negative()). The problem is that the DCACHE_ENTRY_TYPE field of dentry->d_flags may be overridden by the union part of a layered filesystem and isn't thus necessarily indicative of the type of dentry. Normally, this would involve a negative dentry (ie. ->d_inode == NULL) having ->d_layer.lower pointed to a lower layer dentry, DCACHE_PINNING_LOWER set and the DCACHE_ENTRY_TYPE field set to something other than DCACHE_MISS_TYPE - but it could also involve, say, a DCACHE_SPECIAL_TYPE being overridden to DCACHE_WHITEOUT_TYPE if a 0,0 chardev is detected in the top layer. However, inside a filesystem, when that fs is looking at its own dentries, it probably wants to know if they are really negative or not - and doesn't care about the fallthrough bits used by the union. To this end, a filesystem should normally use d_really_is_positive/negative() when looking at its own dentries rather than d_is_positive/negative() and should use d_inode() to get at the inode. Anyone looking at someone else's dentries (this includes pathwalk) should use d_is_xxx() and d_backing_inode(). Signed-off-by:
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Al Viro authored
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- 12 Apr, 2015 14 commits
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Al Viro authored
we can do that now - all we need is to clear IOCB_DIRECT from ->ki_flags in "can't do dio" case. Signed-off-by: -
Al Viro authored
... avoiding write_iter/fcntl races. Signed-off-by: -
Al Viro authored
... returning -E... upon error and amount of data left in iter after (possible) truncation upon success. Note, that normal case gives a non-zero (positive) return value, so any tests for != 0 _must_ be updated. Signed-off-by: -
Al Viro authored
Alignment checks for dio depend upon the range truncation done by generic_write_checks(). They can be done as soon as we got ocfs2_rw_lock() and that actually makes ocfs2_prepare_inode_for_write() simpler. The only thing to watch out for is restoring the original count in "unlock and redo without dio" case. Position doesn't need to be restored, since we change it only in O_APPEND case and in that case it will be reassigned anyway. Signed-off-by: -
Al Viro authored
it's &iocb->ki_pos; no need to obfuscate. Signed-off-by: -
Al Viro authored
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Al Viro authored
it's easier to do generic_write_checks() first Signed-off-by: -
Al Viro authored
already done by caller. We used to call __fuse_direct_write(), which called generic_write_checks(); now the former got expanded, bringing the latter to the surface. It used to be called all along and calling it from there had been wrong all along... Signed-off-by: -
Al Viro authored
simpler that way... Signed-off-by: -
Al Viro authored
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Al Viro authored
all remaining callers are passing 0; some just obscure that fact. Signed-off-by: -
Al Viro authored
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Al Viro authored
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Al Viro authored
A side effect worth noting: in O_APPEND case we set ->ki_pos early, so if it turns out to be an error or a zero-length write, we'll end up with ->ki_pos modified. Safe, since all callers never look at the ->ki_pos after the call of __generic_file_write_iter() returning non-positive, all the way to caller of ->write_iter() and those discard ->ki_pos when getting that. Signed-off-by:
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